183,661 results
Search Results
102. Fostering Students' Modelling and Problem-Solving Skills through Operations Research, Digital Technologies and Collaborative Learning
- Author
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E. Taranto, G. Colajanni, A. Gobbi, M. Picchi, and A. Raffaele
- Abstract
Operations Research (OR) is a branch of applied mathematics that deals with optimization problems arising from different real contexts. The solving process of its problems is based on the construction and resolution of mathematical models, showing the possible connections between mathematics and the real world. Nevertheless, OR is not typically included in most curricula of higher secondary schools (i.e. Grades 9-12), but it is usually presented mainly at university level. To show how OR could be significant for these school students' education, the authors of this paper developed an educational project consisting of three teaching units. In this paper, we share the result of the teaching experiment related to the first unit, addressed to Grade 10. Qualitative and quantitative analyses show how it is appropriate to include OR and its typology of problems in regular school mathematics lectures. Second, these data also show how modelling and problem-solving skills, developed working with OR, can be fostered by implementing a collaborative way of working, also by making use of digital technologies. Last but not least, we demonstrate the positive impact such activities have on students' appreciation of OR.
- Published
- 2024
- Full Text
- View/download PDF
103. An Introduction to Modelling through a Microbial Interaction Application
- Author
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Fabiana Zama
- Abstract
This paper describes a teaching experiment in a Numerical Methods course for Master of Science students. The experiment uses scientific papers to develop modelling studies in the context of wine fermentation microbial interactions. The course involves theoretical and laboratory classes that focus on implementing numerical methods using Matlab for Initial Value Problems and Boundary Value Problems. The students are asked to formalise the mathematical model and build their own experiments using the information provided in the papers. Additionally, a parameter estimation experiment is organised, which involves generating synthetic data and computing noisy data to estimate the natural death rate of sensitive yeast. The results show that data noise significantly affects the parameter estimate and that scaling the data can help reduce the impact of measurement errors. The presented results can be used to investigate other possible assignments, such as how the evaluation of the Jacobian affects the estimation performance and compare different optimisation algorithms.
- Published
- 2024
- Full Text
- View/download PDF
104. Study on Space Charge Characteristics of Transformer Insulating Paper Under Different Working Conditions.
- Author
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Zhang, Yiyi, Wang, Gang, Zhang, Xingtuo, Zhong, Wenbo, Su, Zhicheng, Xu, Chuqi, Wang, Running, Mao, Xinyang, and Liu, Jiefeng
- Subjects
SPACE charge ,ELECTRIC charge ,ELECTRIC distortion ,DYNAMIC balance (Mechanics) ,TRANSFORMER insulation - Abstract
The space charge effect of transformer insulating paper will distort its internal electric field, and its space charge effect will be more prominent under extremely complex working conditions. At present, the micromechanism of charge transport and electric field distortion characteristics of paperboard are not clear under complex working conditions. So in this article, based on the bipolar carrier transport (BCT) model and the dynamic carrier balance model, the effects of high temperature, aging degree, moisture content, and bent degree on charges accumulation in paperboard are studied under dc high voltage by numerical simulation and the measured data needed for simulation. The results show that the higher temperature strengthens the carrier migration, deepens the injection depth of the charge, and aggravates the distortion of electric field intensity in paperboard. The more extended the aging time of paperboard, the greater the internal trap density and the deeper the trap depth, which lead to charges migration difficultly. Increasing water content in the paperboard will accelerate space charges to reach a steady state, while further increasing it will slow down this process, which is related to the shallow trap getting deeper. When the critical part of paperboard is extruded, many traps are introduced, resulting in charges accumulation seriously. The research results can reference the design of paperboard and the maintenance of transformer insulation system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
105. A SEMI-EMPIRICAL MODEL OF THE TENSILE ENERGY ABSORPTION OF SACK KRAFT PAPER
- Author
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Paul Shallhorn and Norayr Gurnagul
- Subjects
Kraft papers ,Bag papers ,Rupture work ,Pulp properties ,Paper properties ,Water retention ,Tensile strength ,Stretch ,Toughness ,Fiber length ,Mathematical models ,Biotechnology ,TP248.13-248.65 - Abstract
We have developed a semi-empirical model to relate the tensile energy absorption (TEA) of paper sheets formed from high-consistency refined pulp to pulp properties, including water retention value (WRV), fibre length, and fibre curl. TEA is shown to be related to the normalized stretch (ratio of stretch to tensile strength) and the tensile strength of the pulp. Normalized stretch appears to be a function of fibre curl, whereas tensile strength for a given pulp is a function of the fibre length, fibre curl, and WRV. The manner in which these three pulp properties develop in a given refining operation determines the development of TEA.
- Published
- 2010
106. Abstracts of contributed papers
- Published
- 1994
107. The history of NATO TNF policy: The role of studies, analysis and exercises conference proceedings. Volume 2: Papers and presentations
- Author
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Rinne, R
- Published
- 1994
108. Overconsumption as a function of how individuals make choices: A paper in honor of Howard Rachlin's contributions to psychology.
- Author
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Heyman, Gene M.
- Subjects
- *
FISCAL policy , *MATHEMATICAL models , *CONSUMPTION (Economics) , *CONSUMERS , *SELF-control - Abstract
Howard Rachlin's widely influential behavioral economic approach to self‐control and related issues provides the model for this submission. The topic is overconsumption. Current human consumption levels are unsustainable. Explanations typically focus on societal factors, such as the seductive power of advertising and/or misguided tax policies. However, the effectiveness of these factors depends on the degree to which individuals are susceptible to the message: "consume more." Humans are not blank slates. This paper argues that how individuals frame their choices establishes the susceptibility to overconsume. According to economic theory, consumers frame their options as bundles, composed of different combinations of the available items and activities. This leads to maximizing. In experiments, participants tend to frame their options as "either‐or" choices. This leads to the matching law. Mathematical models of concurrent schedule choice procedures show that (1) the matching law implies overconsumption of the most preferred option and (2) that individuals will persist in preferring their favorite option even when doing so reduces overall reward rates. Given that the matching law better describes how individuals choose than does maximizing, the mathematical models of widely used choice procedures help explain why efforts to increase consumption have been more influential than efforts to control consumption. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
109. Temperature dependence of methanol and the tensile strength of insulation paper: kinetics of the changes of mechanical properties during ageing.
- Author
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Arroyo, Oscar, Jalbert, Jocelyn, Fofana, Issouf, and Ryadi, Mohamed
- Subjects
METHANOL ,INSULATING paper ,TENSILE strength ,TEMPERATURE effect ,DYNAMICS ,MATHEMATICAL models ,MECHANICAL behavior of materials ,STATISTICAL correlation ,DEPOLYMERIZATION - Abstract
This paper reports the temperature-dependence of methanol generation and the tensile index under ageing conditions for two paper/oil systems: one consisting of a standard wood Kraft paper and the other of a thermally-upgraded Kraft paper (TUK). A linear correlation between methanol and the tensile index for these paper/oil systems was observed in a previous study at 170 °C. In the current study, the correlation was extended to a large range of temperatures (150-190 °C). The experimental data were fitted with a modified Calvini's kinetic model, while the Arrhenius equation was used to model the kinetic of changes of the paper's mechanical properties during ageing. Good agreement with the temperature ( lnk vs. 1/ T) was observed for the rate constants of the chain-end group production, methanol formation, and the decrease of mechanical properties. The Arrhenius equation applied to this data grouping showed activation energy of 130 ± 29 kJ/mol for the decrease in mechanical strength of the standard Kraft paper, while the value was 118 ± 55 kJ/mol for the TUK paper. These values are of the same order of magnitude as those obtained in this study and in the literature for the depolymerization of cellulose and the generation of methanol that was reported. This confirmed the close relationship between cellulose depolymerization, methanol generation and the reduction of the paper's mechanical strength during ageing, dominated by the acid hydrolysis mechanism. The results, which can be seen as a benchmark and pave the way to further research, provide an opportunity for applying the proposed correlations to estimate the insulation condition in operating transformers. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
110. Prediction Model of Bubble Formation in Oil-Paper Insulation Based on the ITBE Envelope.
- Author
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Yang, Chaojie, Zhao, Tao, Liu, Yunpeng, Zhu, Wenbing, and Gu, Zhaoliang
- Subjects
- *
HENRY'S law , *PREDICTION models , *POWER transformers , *DIELECTRIC strength , *TEMPERATURE effect , *SILICONE rubber , *BUBBLES - Abstract
Due to rapid temperature rise and insulation moisture, bubbles can generate in the oil-paper insulation of oil-immersed power transformers, which can reduce the dielectric strength of oil-paper insulation and even bring about the risk of insulation breakdown. In order to accurately evaluate the conditions of bubble formation, the physical process of bubble formation in oil-paper insulation is studied in this article. Considering the effects of water vaporization, gas dissolution in oil, and moisture migration on bubble formation, a bubble formation prediction model is constructed. Based on Henry’s law, the dissolution equilibrium of gas in oil is taken into consideration and the upper boundary of the initial temperature of bubble effect (ITBE) envelope is obtained in this model. Based on the moisture equilibrium in oil-paper insulation, the bubble formation process caused by the emergence and rapid evaporation of free water is analyzed, and then, the lower boundary of the ITBE envelope is obtained in this model. The model results show that the moisture content of the pressboard and the presence of free water have a great impact on ITBE. Specifically, the higher the moisture content, the lower the ITBE value. In addition, with the further increase of moisture content, the upper and lower boundaries of the ITBE envelope gradually tend to be the same. However, once free water is present on the surface of cellulose, ITBE decreases rapidly to below 120 °C. The model built in this article is of great significance to study the temperature limit of the power transformer. Hence the ITBE envelope can provide an important theoretical reference for reducing the risk of bubble formation during power transformer operation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
111. Inclusive Playground Design
- Author
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Holly Tate, Samantha Anstett, Beth Cooke, Merrie Joy Hrabak, and Jennifer Suh
- Abstract
The mathematics of budgeting and space can lead to a justice-oriented experience for elementary students as they design a proposal for an inclusive playground. The authors' work focused on creating the space for elementary children to see the interconnectedness between mathematics and a community social injustice, lack of inclusive playground access, through community-based mathematical modeling (CBMM). This article highlights how third- and fourth-grade teachers, a math coach, and a university professor (also authors of this paper) collaboratively and thoughtfully engaged in the CBMM cycle.
- Published
- 2024
- Full Text
- View/download PDF
112. Quantitative Reasoning and Covariational Reasoning as the Basis for Mathematical Structure for Real-World Situations
- Author
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Kularajan, Sindura Subanemy and Czocher, Jennifer A.
- Abstract
In this paper we address the question, how do quantitative reasoning and covariational reasoning present as students build structural conceptions of real-world situations. We use data from an exploratory teaching experiment with an undergraduate STEM major to illustrate the explanatory roles quantitative reasoning and covariational reasoning play in, (a) coordinating more than two interdependent quantities, (b) conceiving of real-world situations in more than one way, (c) constructing networks of quantitative relationships, and (d) creating a mathematical expression. We make the case that looking at mathematical model construction through the lens of quantitative reasoning and covariational reasoning may provide insights into students' mathematical decisions as they structure complex real-world scenarios. [For the complete proceedings, see ED630060.]
- Published
- 2021
113. Basic Mathematical Modelling Competencies for Non-STEM Higher Education
- Author
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Marchisio, Marina, Roman, Fabio, and Sacchet, Matteo
- Abstract
The role of mathematical modelling pertains several disciplines, both STEM and non-STEM, and various fields: education, academy, work, everyday and social life. Despite its importance, it is not uncommon to see university students facing difficulties with the use of Mathematics to create models, even when mathematical entities that play a role in facing a problem belong to the study programs of secondary schools, and should thus be familiar also to students without a specific background in Mathematics. Difficulties can arise in various phases of modelling: in the comprehension of the problem, in the translation into mathematical formulas, in the resolution process or even in the interpretation of the results. In this paper, we give an analysis of an online test taken by 75 non-STEM students. The 10 questions of the test focused on specific items in mathematical modelling. During the test, students had to write down the reason why they chose a specific answer. The test allowed us to find and categorize the common errors students make and the phase in which it happens, suggesting actions in order to prevent them. Results show percentages of errors and discuss students' arguments. [For the full proceedings, see ED621892.]
- Published
- 2021
114. A Mathematical Model for Reduction of Trim Loss in Cutting Reels at a Make-to-Order Paper Mill.
- Author
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Khan, Razaullah, Pruncu, Catalin Iulian, Khan, Abdul Salam, Naeem, Khawar, Abas, Muhammad, Khalid, Qazi Salman, and Aziz, Asnaf
- Subjects
PAPER mills ,CUTTING stock problem ,SIMPLEX algorithm ,MATHEMATICAL models ,LINEAR programming - Abstract
One of the main issues in a paper mill is the minimization of trim loss when cutting master reels and stocked reels into reels of smaller required widths. The losses produced in trimming at a paper mill are reprocessed by using different chemicals which contributes to significant discharge of effluent to surface water and causes environmental damage. This paper presents a real-world industrial problem of production planning and cutting optimization of reels at a paper mill and differs from other cutting stock problems by considering production and cutting of master reels of flexible widths and cutting already stocked over-produced and useable leftover reels of smaller widths. The cutting process of reels is performed with a limited number of cutting knives at the winder. The problem is formulated as a linear programming model where the generation of all feasible cutting patterns determines the columns of the constraint matrix. The model is solved optimally using simplex algorithm with the objective of trim loss minimization while satisfying a set of constraints. The solution obtained is rounded in a post-optimization procedure in order to satisfy integer constraints. When tested on data from the paper mill, the results of the proposed model showed a significant reduction in trim loss and outperformed traditional exact approaches. The cutting optimization resulted in minimum losses in paper trimming and a lesser amount of paper is reprocessed to make new reels which reduced the discharge of effluent to the environment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
115. Mathematical Knowledge and Skills of University Students When Solving a MEA = Conocimientos y Habilidades Matemáticas de Estudiantes Universitarios al Realizar una MEA
- Author
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Rodríguez-González, Iván I., Vargas-Alejo, Verónica, and Montero-Moguel, Luis E.
- Abstract
In this paper we present the results of an investigation related to the developing of mathematical knowledge and skills by first semester university students when solving a Model Eliciting Activity [MEA] which involves quadratic function knowledge. This was a qualitative research. The theoretical framework was Models and Modeling Perspective [MMP]. The results show that the students used their mathematical knowledge and skills related to linear and quadratic functions to describe the situation; they moved from a quantitative cycle of understanding (associated with linear and quadratic behaviors), to an algebraic cycle of understanding (associated with quadratic behaviors). [For the complete proceedings, see ED629884.]
- Published
- 2020
116. How Mathematical Modeling Enables Learning?
- Author
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Kandasamy, Sindura Subanemy and Czocher, Jennifer
- Abstract
In this theoretical paper we compare the Piagetian perspective on knowledge construction to mathematical model construction, with the aim to understand how mathematical modeling enables learning of mathematics and learning of science, as is often claimed. We do this by examining data through two lenses: (1) examining the role of cognitive conflict as it arises during validation of a model; and (2) viewing model validation as a reflection on activity-effect relationship. We explain why we chose to look deeply into model validation specifically, present examples for each lens, and consider implications. [For the complete proceedings, see ED629884.]
- Published
- 2020
117. So delicate yet so strong and versatile - the use of paper in objects conservation.
- Author
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Artal-Isbrand, Paula
- Subjects
WORKMANSHIP ,CELLULOSE ,SOLVENTS ,MANUSCRIPTS ,MATHEMATICAL models - Abstract
A large variety of acid-free Asian and Western papers offer objects conservators numerous applications in their work. Not only have objects conservators borrowed this extraordinary material - paper - from the field of paper conservation but they have also adopted many of the well-developed methods and techniques of handling and manipulating it in their 3-D treatments. Paper meets all material criteria in modern conservation practice, including reversibility, strength, inertness, long-term stability, minimal change in color over time, and compatibility with the original artwork. Additional attractive characteristics are that it is light weight, non-toxic, hydrophilic, it conforms well to surfaces, and is not affected by the solvents typically used. Also, the cost of paper varies but is not excessively high. Finally, having the option of using paper in sheet, fiber or powder form - either in a dry or wet state - allows for even wider applications. This article is a survey of the wide range of applications of paper in objects conservation. Its use can have two very different functions. It can serve as a restoration material, thereby remaining with the artwork after the treatment is complete, and as a tool during treatment, thereby not remaining with the artwork after the treatment is complete. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
118. Some Comments on Macdonald's Paper
- Author
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Griffiths, Brian
- Published
- 1978
119. Error Noted in a Paper by Jacobs, Silan, and Clemson
- Author
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Baki, Md. Fazle
- Published
- 1998
120. Synergic effect of recycled paper sludge and expanded perlite on the engineering properties of porous clay bricks: A new mathematical modelling approach.
- Author
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Sutcu, Mucahit, Ozturk, Savas, and Gencel, Osman
- Subjects
- *
BRICKS , *RECYCLED paper , *PERLITE , *WASTE paper , *PAPER recycling , *MATHEMATICAL models - Abstract
• Combined effects of extruded brick compositions with paper sludge and expanded perlite were characterized. • The use of additives in bricks has significantly affected their thermo-physical and mechanical properties. • The effects of process parameters on brick properties were investigated with a new mathematical modeling approach. • Fired brick samples showed good thermal insulation performance. • Produced exruded bricks have good potential for energy saving. Lightweight bricks produced with addition of different additive materials such as expanded perlite (EP) and recycling paper sludge (RPS) waste have been accomplished by a pug mill. Porous fired bricks were produced by using organic and inorganic additives such as paper waste and expanded perlite as pore-makers. In the experimental study, the seventeen mixture sets were prepared with Box-Behnken experimental design procedure of two additive ratios and firing temperatures. The brick samples were produced with shaping by extrusion method and firing at 850, 950 and 1050 °C for two hours after drying. Physical characteristics such as bulk density, apparent porosity and water absorption, and also, compressive strength, thermal conductivity and microstructural properties of brick samples were studied. Influences of process parameters on brick properties were investigated with a detailed neuro-regression analysis. In conclusion, the best brick composition (10 % EP + 10 %RPS by weight) in terms of thermal conductivity corresponding to acceptable mechanical properties was optimized. Accordingly, the compressive strength values of all samples are around 10 to 27 MPa. Also, the samples with high additive content (especially 10 %RPS + 5 %EP sample) exhibited the lowest thermal conductivity value (0.432 W/mK) due to the low firing temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
121. Modeling and Optimization of Agronomic Factors Influencing Yield and Profit of a Single-Cropping Rice Cultivar
- Author
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Liu, Weiming, Bao, Zuda, Rannenberg, Kai, Editor-in-chief, Sakarovitch, Jacques, Series editor, Goedicke, Michael, Series editor, Tatnall, Arthur, Series editor, Neuhold, Erich J., Series editor, Pras, Aiko, Series editor, Tröltzsch, Fredi, Series editor, Pries-Heje, Jan, Series editor, Whitehouse, Diane, Series editor, Reis, Ricardo, Series editor, Furnell, Steven, Series editor, Furbach, Ulrich, Series editor, Gulliksen, Jan, Series editor, Rauterberg, Matthias, Series editor, Li, Daoliang, editor, and Li, Zhenbo, editor
- Published
- 2016
- Full Text
- View/download PDF
122. Fuzzy Linguistic Variables in Mathematical Activities in Kindergarten
- Author
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Jankovic, Branka and Magzan, Maša
- Abstract
In this paper, the application of fuzzy logic in mathematical education is viewed from the perspective of pre- school education. The aim of the paper is to give a brief overview of examples from the literature related to fuzzy logic and to point out the presence of fuzzy linguistic variables in the everyday life of a preschool child, as well as the importance of developing and respecting the approximate reasoning of preschool children. Although crisp mathematics requires crisp arguments that characterize our cognitive development, preschoolers start from common argumentation and use vague words. Fuzzy logic is an excellent tool for supporting such approximate reasoning which allows preschoolers to model real-life situations using vague words.
- Published
- 2020
123. Multiple-choice knapsack-based heuristic algorithm for the two-stage two-dimensional cutting stock problem in the paper industry.
- Author
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Kim, Kyungdoc, Kim, Byung-In, and Cho, Hyunbo
- Subjects
CUTTING stock problem ,MATHEMATICAL optimization ,MATHEMATICAL models ,HEURISTIC algorithms ,KNAPSACK problems ,PAPER mills - Abstract
This study examines a two-stage two-dimensional cutting stock problem encountered by a paper mill company. The problem includes various machine-related and operational constraints based on real-world situations. Paper products are manufactured using two major cutting processes. Each cutting machine has a specific minimum and maximum width for input and output rolls and is limited by the maximum number of rolls it can cut at the same time. A mathematical model is presented to formally address the problem and an efficient multiple-choice knapsack-based heuristic algorithm is proposed to solve the problem. To demonstrate the efficiency of the proposed heuristic algorithm, computational experiments are conducted on test data-set generated from real-world data provided by a large paper mill company in the Republic of Korea. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
124. Telecommunications Policy Research Conference. Competition in the Local Loop Section. Papers.
- Author
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Telecommunications Policy Research Conference, Inc., Washington, DC.
- Abstract
Four papers consider competition, new technology and economics of local telephone companies in a deregulated environment: (1) "An Engineering and Policy Analysis of Fiber Introduction into the Residential Subscriber Loop" (Marvin Sirbu, Frank Ferrante, and David Reed); (2) "Competition in the Local Loop: Pricing Carrier Access" (Steve G. Parsons); (3) Default Capacity Tariffs: Smoothing the Transitional Regulatory Asymmetrics in the Telecommunications Marketplace" (Dennis Weisman) (abstract only); and (4) "The Economics of Bypass in a Simple Model of the Telephone Network" (Glenn A. Woroch). The first paper is supplemented by 14 figures and 46 references, and the fourth paper includes a stylized model and six references. (EW)
- Published
- 1987
125. Telecommunications Policy Research Conference. Standards and Standardization Section. Papers.
- Author
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Telecommunications Policy Research Conference, Inc., Washington, DC.
- Abstract
These three papers consider various models and mechanisms for the achievement of industrial standardization. The first, "Duopoly Compatibility Standards with Partial Cooperation and Standards Leadership" (Sanford V. Berg, University of Florida) presents a model of duopolists producing differentiated substitutes, and considers the equilibrium outcomes for two products under Cournot rivalry, multiproduct monopoly, second-best standards-specification, and welfare maximization. The text is supplemented with two tables. The second paper, "The Economics of Gateway Technologies and Network Evolution: Lessons from Electricity Supply History" (Paul A. David and Julie Ann Bunn, Stanford University), examines the historical development of the technology of electric light and power systems, with particular attention to the role which the induced invention of a compatibility-creating technical device (the rotary converter) played in the industry's technological and organizational development. The text is extensively footnoted, and 71 references are provided. The third paper, "Coordination through Committees and Markets" (Joseph Farrell, University of California at Berkeley, and Garth Saloner, Massachusetts Institute of Technology), discusses two common mechanisms--standardization committees and "market leadership"--for achieving coordination, with particular reference to the choice of compatibility standards. The text is supplemented with figures, and is extensively footnoted. A list of 25 references is also provided. (Author/EW)
- Published
- 1987
126. The Coastal Ocean Prediction Systems program: Understanding and managing our coastal ocean. Volume 2: Overview and invited papers
- Published
- 1990
127. Comments on the geophysics paper -- Multiparameter l(1) norm waveform fitting: Interpretation of Gulf of Mexico reflection seismograms: by H. Djikpesse and A. Tarantola
- Author
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Symes, W
- Published
- 2000
128. Energy system diagnosis of paper-drying process, Part 2: A model-based estimation of energy-saving potentials.
- Author
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Chen, Xiaobin, Li, Jigeng, Liu, Huanbin, Yin, Yongjun, and Zhang, Yanzhong
- Subjects
- *
MATHEMATICAL models , *PAPER industry , *ELECTRIC power consumption , *BENCHMARKING (Management) , *TOTAL quality management - Abstract
The pulp and paper sector is the fourth largest industrial sector in terms of energy use in the world. Of the numerous processes involved in paper-making by a paper machine, the dryer section is the process that consumes the largest amount of energy. A model-based method for estimating energy-saving potentials of the dryer section was put forward in the present study. It was done by four steps: establishing a mathematical model about energy consumption, determining the model parameters, benchmarking the drying performance to obtain the corresponding energy-saving measures, and estimating the energy-saving potentials by using the mathematical model. In a case study, a multi-cylinder dryer section was selected to illustrate the method. After a fundamental field test and observation, several operating problems that restricted the energy performance of paper drying were found. And then several reasonable energy-saving measures were suggested to the operators. Finally, applying the mathematic model, it was found that 0.32 ton of steam will be saved when producing 1 ton of paper in recommended operating conditions. With the designed capacity of 200,000 tons/year, the annual steam-savings will be 64,000 tons. Generally, the price of steam is 130–150 Chinese Yuan (about US$21–24) in China, and the annual economic benefits will be 8.32–9.60 million Chinese Yuan (about US$1.344–1.536 million). [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
129. An Equilibrium Model of Urban Population and the Distribution of Income. Discussion Paper 355-76.
- Author
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Wisconsin Univ., Madison. Inst. for Research on Poverty., Yinger, John, and Danziger, Sheldon
- Abstract
The relationship between the level of income and the population of an urban area is a familiar concern in urban economics. Existing models of the relationship between income levels and urban population are considered to assume that there is a homogeneous labor force and, hence, a world in which there is no inequality in the size distribution of income within an urban area. In this paper, a world is modeled in which there are two classes of workers and the relationship between urban population and the distribution of income between these two classes is examined. In particular, it is determined what happens to the degree of inequality in money incomes as urban population increases, if each class of worker is compensated for the higher costs associated with larger urban size. The analysis in this paper is based on a mathematical model of an urban area which allows us to calculate how the income distribution--as measured by a Gini coefficient--changes as urban population changes. This model is solved numerically for a variety of assumptions about the initial size of the urban population and its division between skill classes, initial income distribution, commuting costs, and several other parameters. The findings of the simulations using this model are then tested using data for a sample of metropolitan areas. (Author)
- Published
- 1976
130. Departmental Enrollment Projection Model. AIR Forum 1979 Paper.
- Author
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Toporovsky, R. H.
- Abstract
The Departmental Enrollment Projection Model (DEPM), which is based on the assumption that enrollments are essentially influenced by economic and social forces, is described. Under the model's approach, the department, rather than the institution as a whole, is seen as the focal point of both the enrollment projection and, by implication, the planning strategies. The pool of students individual departments are now concerned with is that of potential students, in the relevant higher-education region, contemplating formal training. Quality of education, placement prospects, and relative tuition are factors which can now be directly related to enrollment and controlled in the attainment of institutional and departmental goals. Labor market and education market factors form the economic foundations of the model. The current version of the DEPM has been developed as a recursive system of four behavioral, one trend, and one policy or control equations for each program or department of instruction. Restrictively, each department's direct enrollments are assumed to be independent from the other departments. Equations used in the model are presented and discussed. The data concepts and sources of information used in the model are summarized. The effect of specification, exogenous variables, and policy variations are also described. (SC)
- Published
- 1979
131. The Use of Multiple Regression and Trend Analysis to Understand Enrollment Fluctuations. AIR Forum 1979 Paper.
- Author
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Campbell, S. Duke and Greenberg, Barry
- Abstract
The development of a predictive equation capable of explaining a significant percentage of enrollment variability at Florida International University is described. A model utilizing trend analysis and a multiple regression approach to enrollment forecasting was adapted to investigate enrollment dynamics at the university. Four independent variables were used in a stepwise linear regression analysis to explain variance in the total university full-time-equivalent enrollment. Three of the four variables used are presently employed in business forecasting models to account for changes caused by trends, seasonal variations, and cyclical variations. The fourth variable was introduced to account for the opening and operation of a new campus. The model accounts for 99.6 percent of the variation observed in total university enrollments for the past 20 quarters and provides estimates of the enrollment within one percent of the enrollments actually observed. The model also has the potential for making reasonably accurate and reliable short-range enrollment forecasts. The model demonstrated that changes in economic conditions in the county, reflected by changing unemployment rates, correlate significantly and positively with changes in total university enrollment. Total university enrollment did not change from its second to its sixth year of operation except for those changes that could be accounted for by changes in unemployment in the county. The opening and operation of the new campus increased total university enrollment by about six percent. (SC)
- Published
- 1979
132. The Search for Better Predictors of Incomes of High School and College Graduates. AIR Forum 1979 Paper.
- Author
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Witmer, David R.
- Abstract
A search for better predictors of incomes of high school and college graduates is described. The accuracy of the prediction, implicit in the work of John R. Walsh of Harvard University, that the income differences in a given year are good indicators of income differences in future years, was tested by applying standard statistical procedures to data describing the annual incomes of men 25 years old and older during the period 1956 to 1975. Addition of the gross national product in the year prior to the previous equation yields much improved results. Application of Richard B. Freeman's three-equation recursive adjustment model indicates that the starting salaries of college graduates are not good correlates of income differences. Several sets of data from the American Council on Education "Fact Book on Higher Education" were then entered into a series of multiple correlation and regression studies. Studies of the 184 independent variables identified four that, taken together, yield significantly better predictions of future income differences. These factors were: (1) male population 22 years old, 13 years prior; (2) male college graduates at the B.A. and first-professional degree level/male population 29 years old, 11 years prior; (3) male college graduates at the B.A. and first-professional degree level, 14 years prior; and (4) male college graduates at the B.A. and first-professional degree level/male population 29 years old, 14 years prior. However, no theory to explain the connections among these variables is apparent. (SC)
- Published
- 1979
133. Estimating Errors in Student Enrollment Forecasting. AIR Forum 1979 Paper.
- Author
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Marshall, K. T. and Oliver, R. M.
- Abstract
The use of data on longitudinal student attendance patterns to determine variances, and hence confidence bounds, on student enrollment forecasts, in addition to finding the forecasts themselves, is demonstrated. The formulation of the enrollment model based on longitudinal student attendance patterns is described step by step, presenting the equations used in the model and some sample data obtained through application of the model. Applications of various equations are demonstrated. The model is analyzed assuming that the new admissions each period follow a Poisson distribution. The enrollment permits the development of statements about the approximate behavior of the conditional distribution of the total number of students in attendance at a given time. It is assumed that entering cohorts contain large numbers of students. Equations relative to this function are presented and discussed. Sample data on the forecasts and confidence intervals for each semester enrollment are presented. The model provides a measure of the error that could be present for each forecast. (SC)
- Published
- 1979
134. Replicating Freeman's Recursive Adjustment Model of Demand for Higher Education. AIR Forum 1979 Paper.
- Author
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Wish, John R. and Hamilton, William D.
- Abstract
The viability of Freeman's Recursive Adjustment Model as a management tool for explaining and predicting enrollments and the job market is examined using macro and micro cases. To establish a relationship between college attendance and the college job market, Freeman employed a 3-equation model to analyze the causative supply and demand determinants. Freeman's equations and published and unpublished data are used to ascertain the goodness of fit for the entire United States, the entire state of Oregon, the University of Oregon, and two major departments at the University of Oregon (business and psychology). Freeman's model is presented, its application is discussed, and the method utilized to test Freeman's model is described. The study results suggest that Freeman's model for explaining college enrollments and graduate job market could be effectively employed by university administrators and institutional researchers to help analyze the major determinants in college attendance. The model might be more valid for the larger macro entities, such as national, state, or university, than it is for the smaller micro entities. The study results indicate that the degree of fit for the model on the micro level will vary considerably from university department to university department and on the general availability of the required data. (SC)
- Published
- 1979
135. Bayesian Decision Theory in Enrollment Forecasting. AIR Forum 1979 Paper.
- Author
-
Lind, Douglas A.
- Abstract
The use of subjective probability as a theoretical model for enrollment forecasting is proposed, and the results of an application of subjective probability to enrollment forecasting at the University of Toledo are reported. Subjective probability can be used as an enrollment forecasting technique for both headcount and full-time equivalent using the following steps: (1) assume the various subpopulations are normally distributed; (2) determine the mean and standard deviations of these subpopulations; (3) sum the means and variances of the subpopulations to obtain the mean and variance of the university forecast; and (4) perform a linear transformation on the headcount distribution to obtain the full-time equivalent distribution. Major advantages of this method are: it allows the study of homogeneous subpopulations; it allows comparisons with other methods, since the variability is known; and it allows probability statements regarding various headcount and full-time equivalent outcomes. Application of the subjective probability method to enrollment forecasting at the University of Toledo resulted in a difference of 0.4 percent between the actual and the forecasted headcount enrollment and a difference of 0.3 percent between actual and forecasted full-time equivalent enrollment. In comparison with the conventional forecasting techniques also employed in the test study, the forecasting errors using the subjective probability were the smallest. (SC)
- Published
- 1979
136. Estimation of the Reliability of a Test Consistency of More Than Three Congeneric Parts. Iowa Testing Programs Occasional Papers, Number 28.
- Author
-
Mayekawa, Shin-ichi and Haebara, Tomokazu
- Abstract
A least squares approach to estimating the reliability of a measure consisting of more than three content homogeneous or congeneric parts is proposed. The advantages of this method over a more indirect approach in which certain parts of a measure are combined to use Kristof's or Feldt's coefficients are examined. One hundred four-part tests were created by randomly assigning certain items from a 48-item mathematics achievement test to each of the four parts. Data on 400 examinees who took the test were divided into five subsets. Seven estimates of reliability were computed for 100 random splits for each subset of data. Some of the main results included: (1) there is a consistent order in the magnitudes of the means of the coefficients, regardless of sample size; (2) values of the average of the Kristof coefficients are greater than unity when sample size is small; (3) the proposed coefficient has smaller standard deviation and range than the Kristof coefficient; and (4) the Feldt coefficient tends to have smaller standard deviation and range than the proposed coefficient, and depends on the assumption that the error variance of a part is proportional to its length. (Author/RL)
- Published
- 1980
137. The Learning of Number Facts in the Primary School. Curriculum Paper.
- Author
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Queensland Dept. of Education, Brisbane (Australia). and Boxall, Ron
- Abstract
This paper is designed to provide teachers with more guidance on how to help students become proficient in the recall of basic number facts. Activities and practices are placed in a sequence designed to aid all instructors. The learning of number facts is divided into three stages: (1) the development of basic number facts; (2) establishing number facts; and (3) the memorization of basic number facts. The position adopted is that there is a need for children to have the ability to recall basic number facts readily. This paper confines itself to whole number operations in addition, multiplication, subtraction, and division. Although this material was originally designed for elementary teachers, these materials could be adapted to junior and senior high school use where drill and refreshment in basic number facts is necessary by modifying activities, problem activities, and vocabulary. (MP)
- Published
- 1979
138. Staff Adequacy in Michigan Public Schools. School Finance Project Working Paper #1. Revised.
- Author
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Michigan State Dept. of Education, Lansing., Phelps, James L., and Addonizio, Michael F.
- Abstract
This paper, one of three related documents, examines statewide trends in the distribution of staff in the Michigan public schools. Along with its related documents, it provides a basis for analyzing the impact of state financing mechanisms and funding levels on the overall distribution of resources throughout the state and on the resource allocation and programmatic decisions of the individual school districts. This paper begins with a breakdown of aggregate staffing and staffing ratios and concludes with a discussion of educational equity, equality, and excellence. Graphs and tables are included. (Author/LD)
- Published
- 1979
139. A Model and a Metric for the Analysis of Status Attainment Processes. Discussion Paper No. 492-78.
- Author
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Wisconsin Univ., Madison. Inst. for Research on Poverty. and Sorensen, Aage B.
- Abstract
This paper proposes a theory of the status attainment process, and specifies it in a mathematical model. The theory justifies a transformation of the conventional status scores to a metric that produces a exponential distribution of attainments, and a transformation of educational attainments to a metric that reflects the competitive advantage conferred by education. The new metric produces theoretically more meaningful results than the old metric when used together with the proposed model in an analysis of change in status; and also performs better statistically with the proposed model, as well as with conventional models for the level of status. An empirical analysis demonstrates that there are less favorable career opportunities for women compared to men and for blacks compared to whites. (Author)
- Published
- 1978
140. Catastrophe Theory in Higher Education Research. AIR Forum 1981 Paper.
- Author
-
Staman, E. Michael
- Abstract
The applicability of catastrophe theory to research in higher education is considered, with several problems that typically appear in the literature presented in a theoretical framework. A catastrophe model is attempted for each. The nature of mathematical modeling and the relationship between modeling continuous systems and discontinuous systems are assessed. Characteristics that must be present in a system for it to be suitable for a catastrophe theory based model are bimodality, divergence, discontinuity or catastrophe, hysteresis, and inaccessibility. Attention is also directed to interpreting a catastrophe surface. Four issues pertaining to the use of catastrophe theory as a tool for modeling behavior in the social sciences are as follows: its foundations of the theory in mathematics and natural philosophy; the assumptions needed for its application; details surrounding specific applications; and the attitudes, style, and intellectual honesty of its advocates. Hypothetical examples for applying the theory are considered: faculty vitality as a function of promotion difficulty and percent of junior faculty hired, teacher expectations as a function of student communication and performance, and student attrition as a function of previous academic performance and educational aspirations. Based on the literature on catastrophe theory, it is suggested that the bridges between the theoretical applications and those actual applications where theory can be tested through quantification have begun to be built. It is concluded that the usefulness of the theory may come from the ability of its models to provide more complete, and possibly more precise, description than appears possible with theories describing continuous behavior. Additionally, graphs based on the theory provide good conceptual tools. A bibliography is appended. (SW)
- Published
- 1981
141. Material flow analysis of paper in Korea. Part I. Data calculation model from the flow relationships between paper products.
- Author
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Hong, Seok-jin, Choi, Yoon-sil, Kim, Kyoung-ryun, Kang, Joon-gu, Oh, Gil-jong, and Hur, Tak
- Subjects
PAPER industry ,MATHEMATICAL models ,PAPER products ,PAPERMAKING ,DATA analysis ,MANUFACTURING processes ,WASTE paper - Abstract
Abstract: The flows of paper are analyzed throughout the papermaking processes, with the year 2007 and Korea defined as the system boundaries. In practice, the statistical data on the production, import and export of paper or pulp can be collected with relative ease from the government and industrial associations. However, the input data regarding the volumes of pulp and wastepaper used in different paper products, such as newsprint, printing papers, sanitary and household papers, specialty papers, and corrugating board base, are difficult to obtain because such information is generally kept confidential in the course of corporate operations. The production processes of paper products in Korea are modeled using information on raw materials, their compositions and production yields of products in order to identify and quantify the amounts of pulp and wastepaper used in each paper product. The material flows of paper are then analyzed based on the calculation model derived from the correlation of input and output flows between the individual processes throughout the entire paper lifecycle. Accuracy analysis using both mean absolute error (MAE) and mean absolute percent error (MAPE) is conducted to verify the amounts of pulp and wastepaper calculated from the proposed model against the volumes of domestically consumed pulp and wastepaper provided in the national statistics. Although the calculated values for the past (i.e., the 1980s and 1990s) differ to some degree from the statistical values, the data for the 2000s have a relatively higher level of accuracy, with the MAPE of the total pulp and recycling volume at 5.39% and 5.30%, respectively, thus validating the adequacy of the proposed modeling method. The proposed calculation model can be effectively used in the material flow analysis (MFA) of paper to reduce the burden of data collection and obtain relatively accurate results. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
142. Tendencias en Modelación Matemática en Latinoamérica = Latin American Trends in Mathematical Modeling
- Author
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Solares Rojas, Armando, Preciado Babb, Armando Paulino, Peña, Fredy, Ortiz, Andrea, Rosas, Marisol Sandova, Velasco, Remedios Soriano, Vázquez, Vicente Carrión, and Fuentes, Mauricio Farrugia
- Abstract
Throughout the years, Mathematical Modeling has gained international attention, not only in research but also in the development of curricula and its applications in the classroom. However, systematic literary surveys are scarce. In this paper, we present some findings from a survey of 485 international publications related to different aspects of mathematical modeling. While the number of Latin-American publications is rather small compared to the number of international publications, the vitality of the currently discussed themes in this region and their innovative perspectives testify to the international relevance of this developed work on mathematical modeling. [This paper is provided in both Spanish and English. For the complete proceedings, see ED606531.]
- Published
- 2018
143. Shoreline change and storm-induced beach erosion modeling : a collection of seven papers / edited by Nicholas C. Kraus : prepared for Department of the Army, US Army Corps of Engineers.
- Author
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Kraus, Nicholas C., Coastal Engineering Research Center (U.S.), U.S. Army Engineer Waterways Experiment Station, MBLWHOI Library, Kraus, Nicholas C., Coastal Engineering Research Center (U.S.), and U.S. Army Engineer Waterways Experiment Station
- Subjects
Beach erosion ,Coast changes ,Coastal zone management ,Environmental aspects ,Mathematical models ,Planning ,Storm surges - Published
- 1990
144. An Analysis of Education Costs across Local School Districts in the State of Missouri, 1975-76. Working Papers in Education Finance, Paper No. 7.
- Author
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Education Commission of the States, Denver, CO. Education Finance Center. and Chambers, Jay G.
- Abstract
This report presents both a methodology for educational cost index computation and empirical evidence for determining the extent to which Missouri school district expenditures are beyond the control of local decision-makers. The author demonstrates considerable stability in the teachers' salary index from 1974-75 to 1975-76. The report extends previous index computations to cover variables reflecting the underlying causes of regional cost differentials, including administrators' as well as teachers' salaries and district transportation costs. Section 1 summarizes the document. Sections 2-4 provide a review of the study's methodology, an explanation of salary and cost index computation, and a discussion of the data used. The fifth section's analysis of Missouri's educational expenditures includes alternative specifications for determining teacher/administrator salaries and transportation costs, an alternative computation of regional and district cost indexes, and a brief discussion of educational cost index implementation. The report contains nine tables with data on salary and cost variables. Five appendixes include the results of two separate school personnel and school district surveys, a map of Missouri school districts, an updated estimate of the 1974-75 teachers' salary equation, a salary index computation formula, and 20 pages of data with 1975-76 cost indexes for the roughly 1,100 Missouri districts that offer transportation services. (JBM)
- Published
- 1978
145. The Effect of Job Experience on Earnings Among Middle-Aged Men. Institute for Research on Poverty Discussion Papers.
- Author
-
Wisconsin Univ., Madison. Inst. for Research on Poverty. and Leigh, Duane E.
- Abstract
The primary purpose of this paper is to improve on the specification of job experience as measured by current age, minus age at completion of formal schooling. The process of acquiring productive job skills was modeled by first focusing on the determination of the level of first-job occupation and then, given initial occupation, examining the determinants of occupational advancement. The impact of initial occupational level and occupational change on current (1966) wage rates were then examined. In the empirical analysis, separate equations for middle-aged black and white men were estimated to focus on racial differences in the acquisition of labor market experience. The primary finding is that it is work experience accompanied by occupational advancement, rather than work experience per se, that has an effect on the distribution of wage rates. (Author/HD)
- Published
- 1975
146. Standards and Criteria. Paper #10 in Occasional Paper Series.
- Author
-
Western Michigan Univ., Kalamazoo. School of Education. and Glass, Gene V.
- Abstract
The logical and psychological bases for setting cutting scores for criterion-referenced tests are examined; they are found to be intrinsically arbitrary and are often examples of misdirected precision and axiomatization. The term, criterion referenced, originally referred to a technique for making test scores meaningful by controlling the test development process. It has since been applied to a variety of mathematical techniques for setting cutting scores. However, because of the nature of tests and the nature of education, no process of quantification will alter the critical concern, the definition of mastery or of minimal competence, which remains either unanswered or vaguely approximate. Different methods of setting cutting scores may provide widely divergent solutions to a given problem. It is important to recognize that cutting scores are arbitrary. However, no criticism is implied with respect to criterion reference or domain reference as techniques of test construction. (CTM)
- Published
- 1977
147. Young Children's Representation of Addition and Subtraction Problems. Theoretical Paper No. 74. Conceptual Paper No. 4.
- Author
-
Wisconsin Univ., Madison. Research and Development Center for Individualized Schooling. and Moser, James M.
- Abstract
A discussion is presented concerning variables associated with children's representation of certain addition and subtraction problems. Problem components are classified as physical, pictorial, sensual, verbal-spoken, verbal-written, symbolic, or internal. Problems are discussed as abstract (symbolic) or nonsymbolic. Three problem components are identified and discussed: (1) measurable entities, (2) contextual relationships or actions on entities, and (3) characteristics of the missing number. The second component is further broken down into joining, separating, equalizing, part-part-whole, and comparison. Problem structure is also discussed. (MK)
- Published
- 1979
148. A Multiple Group Measurement Model of Children's Reports of Parental Socioeconomic Status. Discussion Papers No. 531-78.
- Author
-
Wisconsin Univ., Madison. Inst. for Research on Poverty., Mare, Robert D., and Mason, William M.
- Abstract
An important class of applications of measurement error or constrained factor analytic models consists of comparing models for several populations. In such cases, it is appropriate to make explicit statistical tests of model similarity across groups and to constrain some parameters of the models to be equal across groups using a priori substantive information. This paper discusses a statistical model developed by K. G. Joreskog for these purposes. The model is applied to children's and parents' reports of parental socioeconomic statuses for several grade levels. The analysis, which includes data from sons' reports of the schooling and occupations of their mothers and fathers, suggests that children do not approach their parents' level of reporting accuracy at the same rate for all characteristics; however, by twelfth grade, sons and parents are equally reliable for all characteristics considered. (Author/GC)
- Published
- 1978
149. Bibliography of Papers on Latent Trait Assessment.
- Author
-
Educational Testing Service, Evanston, IL. and Cohen, Allan S.
- Abstract
This partially annotated bibliography of journal articles, dissertations, convention papers, research reports, and a few books and unpublished manuscripts provides a comprehensive coverage of work on latent trait theory and practice. Documents are arranged alphabetically by author. The period covered ranges from the early 1950's to the present. The bibliography was prepared to assist state and local education agencies make appropriate use of latent trait models in the evaluation of their Title I programs. (Author/CTM)
- Published
- 1979
150. A Process for Testing a Mathematical Model for the Solution of a Practical Problem: Application to Test Equating. LES Paper on Learning and Teaching. Paper #79.
- Author
-
Douglass, James B.
- Abstract
A general process for testing the feasibility of applying alternative mathematical or statistical models to the solution of a practical problem is presented and flowcharted. The system is used to develop a plan to compare models for test equating. The five alternative models to be considered for equating are: (1) anchor test equating using classical test theory; (2) anchor test equating using the one-parameter logistic model; (3) anchor test equating using the three-parameter logistic model; (4) preequating using the one-parameter logistic model; and (5) preequating using the three-parameter logistic model. Sources of estimation instability are identified for the logistic models. Various practical and theoretical problems associated with the general process and test equating are discussed. The equating problem is of interest in its own right and serves to explicate the general process. (Author/RL)
- Published
- 1979
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