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In this paper, I introduce the longitudinal method in general, and more specifically, the method applied in a two-decade-long language shift research project conducted in a Romanian–Hungarian bilingual village, Ketegyhaza (hereinafter LongBiLing: longitudinal study on bilingualism). I will primarily present the language choice changes occurring in the first decade (1990–2001) but I will also give a short review of the findings comparing the two decades. The aim of the project is to find out at what stage the Romanian-Hungarian language shift process is in the Hamers and Blanc’s (1989) unidimensional model of language shift and to what extent the process can be considered gradual (Mesthrie 2001). In a previous article I sought to find out in which bilingual national minority (out of the six) in Hungary sustainable bilingualism was the strongest (Borbely 2015). In this paper, I discuss language use domains (25 language choice situations) in a local community of Hungary’s Romanian national minority investiga...

In this paper we propose a novel method for the segmentation of longitudinal brain MRI scans of patients suffering from Multiple Sclerosis. The method builds upon an existing cross-sectional method for simultaneous whole-brain and lesion segmentation, introducing subject-specific latent variables to encourage temporal consistency between longitudinal scans. It is very generally applicable, as it does not make any prior assumptions on the scanner, the MRI protocol, or the number and timing of longitudinal follow-up scans. Preliminary experiments on three longitudinal datasets indicate that the proposed method produces more reliable segmentations and detects disease effects better than the cross-sectional method it is based upon.

PurposeThis paper aims to explore how the regulator of a global financial centre (GFC) under an international trend of adopting emerging technologies for financial services (Fintech) articulates such opportunities and risks strategically.Design/methodology/approachWith a literature review on the global regulatory environment and the underlying risks related to Fintech, it looks into the formulation and implementation of complementary regulatory policies in the case of Hong Kong as a GFC. Relevant policy documents disclosed by the financial regulator on cybersecurity and pertinent issues are examined.FindingsAdopting a strategic approach that seizes opportunities associated with Fintech, the financial regulator harnesses comprehensive risk-based mechanisms to embrace exposures to cyber risks while promoting institutionalization of cybersecurity among the regulated firms with strategic controls. This study suggests a pathway for the evolution of a profession with both technical and ethical competence for mitigating the emerging risks arising from Fintech. However, such an approach is yet to be tested with respect to efficacy for the unexplored territories of fraud exposures, resulting from swift Fintech developments across borders.Research limitations/implicationsAs Fintech has only emerged rapidly in the recent years, it is not conclusive in this review of performance and effectiveness of the financial regulator in its strategic approach. Further studies may utilize a longitudinal method to analyze and examine the regulatory measures undertaken by financial regulators in various GFCs.Originality/valueThis study reveals a strategic approach adopted by an emerged GFC in embracing Fintech innovation that however brings about unidentified risks and potential frauds to its financial services sector. Pertinent anti-fraud and cybersecurity measures are highlighted.

The metaphor of the leaking pipeline is sometimes used to suggest that some students are lost for STEM as they advance through the educational system. This paper follows a cohort of upper-secondary school students with an interest in STEM from 18 months before their completion of upper-secondary until three years after their completion. Adopting a mixed-methods design, it follows the students' reflections and interests concerning their choice of higher education programme within and/or outside STEM. Only 22% of the students expressed the same interest during the whole period, and 56% changed between different groups of studies, e.g. between STEM and HEALTH. The students' trajectories showed that the leaking-pipeline metaphor is misleading because it suggests a linear and one-way movement, while there were students moving in as well as out of STEM trajectories. The students? reflections showed identity issues at the level of ego identity, the personal identity and the social identity (Coté and Levine). Particular incidents in the students? lives and in the outreach programme they were involved in sparked interests and reflections. These incidents should be considered as elements in a continuous reflection concerning who they are and where they would like to go rather than as critical moments.

The aging of populations worldwide has emerged as an important focus of research and policy. Concomitantly, capturing the daily life of elders is becoming a major task for researchers and service providers. In a mobile internet environment, traditional methods are not adequate to support contextualized information behavior research on the elderly. Based on a comparison of six methods from four perspectives (context, time, user, and data), this paper introduces the mobile experience sampling method (mESM) as an effective approach to the study of elders’ everyday information behaviors. An overview of mESM is presented, and a general three-stage framework is proposed to discuss its implementation. We also offer suggestions to improve the efficacy of mESM in addressing the real conditions and characteristics of the elderly and discuss the method’s advantages, disadvantages and related problems from the perspectives of researchers, elders, and policymakers. Overall, we find mESM to be an ideal longitudinal method for capturing the contextualized day-to-day information behavior of elders.

The longitudinal ventilation method is widely used in extra-long tunnels because of its simple ventilation mode and lower construction and operation costs. This paper originally proposes a new longitudinal ventilation method, the single-channel blowing-in longitudinal method. Only one ventilation channel is set between uphill line and downhill line of main tunnel, and relatively fresh air near the entrance of the downhill line is sent to the section close to the uphill line exit through the ventilation channel. The authors deduced the ventilation theory, design method and applicable conditions in detail, analyzing six cases to reveal the variation regulation of optimal location of single-channel xfit, one-year ventilation energy consumption Pone, total ventilation energy consumption Ptotal, and applicable scope of the tunnel length Lmax. The results suggest the following. (1) The optimal location of single-channel xfit enable the total ventilation energy consumption in serving period Ptotal to be the minimal, but usually it cannot let one-year energy consumption Pone reach the minimum. (2) The single-channel system makes full use of the surplus fresh air and the piston effect of traffic wind in the tunnel, showing a better energy-efficient property from a long-term perspective (3) For the whole serving period, xfit and Ptotal is relatively fixed when the traffic volume changes linearly. Meanwhile, this method has been successfully applied to China Mingtang Mountain Tunnel, and the relevant engineering application experience would be helpful for the similar projects.

This paper investigates the effect of the calculation of the longitudinal location of a wheel rail contact point on the wheelset’s motion in a vehicle dynamic simulation. All current vehicle dynamic software programs assume that the contact between wheel and rail takes place in the vertical plane through the wheelset’s rolling axis. However, when the yaw angle of the wheelset is nonzero, the contact point is situated up to 10 mm from that plane. This difference causes a difference in the yaw moment on the wheelset which is used in the vehicle dynamic simulation. To such an end, an existing analytical method to determine the longitudinal method was validated using a numerical approach. Then vehicle dynamic simulations with both the classic and the new contact location were performed, concluding that using a more accurate contact point location results in a smaller wheelset yaw angle in a vehicle dynamic simulation, although the effect is small.

It is well known that cognitive decline in older adults is of smaller amplitude in longitudinal than in cross-sectional studies. Yet, the measure of interest rests generally with aggregated group data. A focus on individual developmental trajectories is rare, mainly because it is difficult to assess intraindividual change reliably. Individual differences in developmental trajectories may differ quantitatively (e.g., larger or smaller decline) or qualitatively (e.g., decline vs improvement), as well as in the degree of heterogeneity of change across different cognitive domains or different tasks. The present paper aims at exploring, within the Geneva Variability Study, individual change across several cognitive domains in 92 older adults (aged 59–89 years at baseline) over a maximum of seven years and a half. Two novel, complementary methods were used to explore change in cognitive performance while remaining entirely at the intra-individual level. A bootstrap based confidence interval was estimated, for each participant and for each experimental condition, making it possible to define three patterns: stability, increase or decrease in performance. Within-person ANOVAs were also conducted for each individual on all the tasks. Those two methods allowed quantifying the direction, the amplitude and the heterogeneity of change for each individual. Results show that trajectories differed widely among individuals and that decline is far from being the rule.

In this paper we focus on regression analysis of irregularly observed longitudinal data that often occur in medical follow-up studies and observational investigations. The analysis of these data involves two processes. One is the underlying longitudinal response process of interest and the other is the observation process that controls observation times. Most of the existing methods, however, rely on some restrictive models or assumptions such as the Poisson assumption. For this we propose a class of more flexible joint models and a robust estimation approach for regression analysis of longitudinal data with related observation times. The asymptotic properties of the proposed estimators are established and a model checking procedure is also presented. The numerical studies indicate that the proposed methods work well for practical situations. The Canadian Journal of Statistics xx: 1–15; 2015 © 2015 Statistical Society of Canada Resume Les auteurs s'interessent a la regression pour des donnees longitudinales observees de facon irreguliere, une situation frequente dans les etudes comportant un suivi medical et dans les etudes observationnelles. De telles donnees emergent de deux processus : le processus de reponses longitudinales sous-jacent et le processus qui controle les temps d'observation. La plupart des methodes existantes se basent sur des hypotheses ou un modele restrictifs telle que l'hypothese de Poisson. Les auteurs proposent une classe plus flexible de modeles conjoints et une approche robuste d'estimation de la regression pour des donnees longitudinales et leur temps d'observation. Ils etablissent les proprietes asymptotiques de l'estimateur propose et presentent des procedures de verification des hypotheses. Les auteurs presentent egalement des etudes numeriques qui indiquent que les methodes proposees fonctionnent bien dans des situations pratiques. La revue canadienne de statistique xx: 1–15; 2015 © 2015 Societe statistique du Canada

In the health and social sciences, longitudinal data have often been analyzed without taking into account the dependence between observations of the same subject. Furthermore, consideration is rarely given to the fact that longitudinal data may come from a non-normal distribution. In addition to describing the aims and types of longitudinal designs this paper presents three approaches based on generalized estimating equations that do take into account the lack of independence in data, as well as the type of distribution. These approaches are the marginal model (population-average model), the random effects model (subject-specific model), and the transition model (Markov model or auto-correlation model). Finally, these models are applied to empirical data by means of specific procedures included in SAS, namely GENMOD, MIXED, and GLIMMIX.

Social network analysis is one of the most recent areas of research which is being used to analyze behavior of a society, person and even to detect malicious activities. The information of time is very important while evaluating a social network and temporal information based analysis is being used in research to have better insight. Theories like similarity proximity, transitive closure and reciprocity are some well-known studies in this regard. Social networks are the representation of social relationships. It is quite natural to have a change in these relations with the passage of time. A longitudinal method is required to observe such changes. This research contributes to explore suitable parameters or features that can reflect the relationships between individual in network. Any foremost change in the values of these parameters can capture the change in network. In this paper we present a framework for extraction of parameters which can be used for temporal analysis of social networks. The proposed feature vector is based on the changes which are highlighted in a network on two consecutive time stamps using the differences in betweenness centrality, clustering coefficient and valued edges. This idea can further be used for detection of any specific change happening in a network.

This paper traces the learning pathways over a 4‐year period of 12 children learning about evaporation. The findings show the complexity and dependence on context of children's understandings. Detailed transcripts for 2 children are used to demonstrate how understandings of phenomena are framed within a network of personal narratives of self that reflect children's different subjectivities as learners and school children. It is argued that the longitudinal methodology opens up a more complex and nuanced view of children's conceptual learning in school settings than is afforded by cross‐sectional studies and that the focus on individuals over time compels a very different construction of the learner than is represented in mainstream conceptual‐change literature.

In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) assessed over a period of 2 years. We use dynamical system analysis, specifically a second order linear differential equation, to model weekly variability in WMC in a sample of 112 9th graders. In our longitudinal data we use a B-spline imputation method to deal with missing data. The results show a significant negative frequency parameter in the data, indicating a cyclical pattern in weekly memory updating performance across time. We use a multilevel modeling approach to capture individual differences in model parameters and find that a higher initial performance level and a slower improvement at the MU task is associated with a slower frequency of oscillation. Additionally, we conduct a simulation study examining the analysis procedure's performance using different numbers of B-spline knots and values of time delay embedding dimensions. Results show that the number of knots in the B-spline imputation influence accuracy more than the number of embedding dimensions.

In this paper, we discuss our learning and suggestions on how to run a diary study, a user research method appropriate to collect longitudinal data. The diary study is a longitudinal method that allows self-reporting of specific aspects of users' natural behaviors and thoughts [2].To get an in-depth understanding about products and its users, we have conducted diary studies both in Enterprise and Consumer domains. The objectives of these studies were to gather information on the usage patterns; existing users pain points and identify opportunities to improve the product. The findings of these studies have given a closer look at the users' requirements and challenges.

This paper describes the fluctuations of temporal criteria dynamics in the context of professional sport. Specifically, we try to verify the underlying deterministic patterns in the outcomes of professional basketball players. We use a longitudinal approach based on the analysis of the outcomes of 94 basketball players over ten years, covering practically players' entire career development. Time series were analyzed with techniques derived from nonlinear dynamical systems theory. These techniques analyze the underlying patterns in outcomes without previous shape assumptions (linear or nonlinear). These techniques are capable of detecting an intermediate situation between randomness and determinism, called chaos. So they are very useful for the study of dynamic criteria in organizations. We have found most players (88.30%) have a deterministic pattern in their outcomes, and most cases are chaotic (81.92%). Players with chaotic patterns have higher outcomes than players with linear patterns. Moreover, players with power forward and center positions achieve better results than other players. The high number of chaotic patterns found suggests caution when appraising individual outcomes, when coaches try to find the appropriate combination of players to design a competitive team, and other personnel decisions. Management efforts must be made to assume this uncertainty.

'Archive können insofern als Wissensquellen bezeichnet werden, als dass sie Daten aus der Vergangenheit erhalten, die wertvoll für die Zukunft sein könnten. Vor der Entwicklung der modernen IT hatten Archive vor allem mit der Materialflut zu kämpfen, die sie aufzeichnen und klassifizieren mussten und für die sie Findehilfen entwickeln mussten. Die Folge war, dass Archiven selten Zeit und Mittel verblieben, um ihre Quellen und Arbeit zu vermarkten. Archivnutzer konnten nur mit hohem Aufwand das richtige Archiv und die richtigen Informationen im Archiv finden. Der Beitrag erläutert neuere Entwicklungen im Bereich der IT, die Archive leichter auffindbar und damit einer breiteren Öffentlichkeit zugänglich machen kann.' (Autorenreferat) 'Archival institutions have been characterized as the arks of knowledge. This is quite right as they preserve data which are dated in the later past but still valuable in nowadays. Before the development of computer technologies, archival institutions had to cope with the immense amount of information they had to record and classify and also create finding aids so as to help users find what they needed, without any automation. So, the archival institutions did not have the chance to promote their work and they had been usually identified with chaos and specialized users, who only them knew the archives' secrets. Hopefully, the computers' evolution, slowly gave the chance to archives to work faster and preserve a lot of information, in various forms, other than paper.' (author's abstract)

An important problem that arises frequently in medical research is the analysis of data that arise from a repeated measures design. One of the distinctions of this design is dependencies among the data. Generally, there are a number of subjects that are assumed to be independent, and several measurements are taken on each subject, usually corresponding to different time points. These are the repeated measurements and are generally correlated. Longitudinal data models arise when for each subject at each time point a vector of observations is taken. These situations have been studied extensively in the literature. The parametric approach is described in several papers and summarized nicely by Liang, Diggle, and Zeger (1994). One of the unique features of repeated measures data is the correlation structure. This is generally not the focus of the study, but the more accurately the correlation structure is specified, the better the conclusions will be. In this setting, we typically test linear hypothesis on the slope parameters or on the correlation parameters. Diggle, Liang, and Zeger describe several common assumptions for the covariance structure. The simplest is called the uniform correlation model. This model corresponds to the assumption that all the observations have equal variances and correlations. When the observations within a subject are supposed to be exchangeable, then the uniform correlation model is implied. Another common assumption is the exponential correlation model. This allows for the more reasonable assumption that correlation decreases as the time between observations increases. These first two assumptions specify the covariance structure with only a few parameters to estimate. Another assumption is the unstructured covariance model. This model allows for a separate parameter for each element of the covariance^ matrix. While we are more confident the covariance structure is properly modelled, the addition of new parameters has several drawbacks including increased standard errors. With repeated measures data, typical least squares is not preferred. To take into account the correlation structure weighted least squares is used. Weighted least squares is similar to least squares except the quantity it minimizes involves a weight matrix. If the weight matrix is taken to be the identity matrix, then weighted least squares becomes typical least squares. The most efficient choice of a weight matrix is the inverse of the covariance matrix. A problem with weighted least squares is that when interval estimates are desired the variance parameter needs to be estimated. The method of least squares does not do an adequate job of this. Maximum likelihood estimation {MLE) for the slope parameter remains the same as least squares under Gaussian assumptions, and an estimate of the variance can be obtained, though it is biased. The method of restricted MLE solves the problem of biased estimates by first linearly transforming the data to remove the slope parameters. These methods generally work well when the data is "nice." However, when outlying and influential observations are present, these methods are no longer valid since they put too much weight on these certain observations. Thus, other methods are desired which can resist the effects of these outlying observations.

The thermal conductivity of UO2 is usually measured in the laboratory using two different methods: longitudinal or radial. For the comparative longitudinal method, in this paper, we present a general solution to the problem, taking into account the small radial flux always existing in the thermal conductivity measurement. A general solution for the isotropic UO2 cylindrical pellets temperature distribution was obtained $$\theta\left({\rho,z}\right)=\sum\limits_0^\infty{{J_o}\left({{\alpha_n}\rho}\right)}\left({{C_n}\exp\left({-{\alpha_n}z}\right)+{D_n}\exp\left({{\alpha_n}z}\right)}\right)$$ and a similar formula for the upper cylindrical rod used as secondary standard was obtained. With an adequate thermocouples distribution, which is described in the paper, it is possible to evaluate the heat fluxes in any sections of the selected secondary standard and over the specimen whose thermal conductivity we are interested in: UO2 in our case. If we designate for αn, An, Bn, and βn, Cn, Dn the parameters which characterize the temperature distribution in the upper rod (secondary standard) and the UO2 cylindrical pellet, for two sections at the very neighbourhood, we obtain φ1 = φ2 and $${\lambda_{U{O_2}}}={\lambda_S}{\left({\sum{_1^2}+\sum{_2^2}}\right)^{1/2}}/{\left({\sum{{{_1^1}^2}}+\sum{{{_2^1}^2}}}\right)^{1/2}}$$ where: $$\sum{_1 =\frac{\delta}{{\delta\rho}}}\sum\limits_0^\infty{{J_O}\left({{\alpha_n}\rho}\right)}\left({{A_n}\exp\left({-{\alpha_n}z}\right)+{B_n}\exp\left({{\alpha_n}z}\right)}\right)$$ $$\sum{_2=\frac{\delta }{{\delta z}}}\sum\limits_0^\infty{{J_O}\left({{\alpha_n}\rho}\right)}\left({{A_n}\exp\left({-{\alpha_n}z}\right)+{B_n}\exp\left({{\alpha _n}z}\right)}\right)$$ and similarly for $$\sum{_1^1} and\sum {_2^1}$$ $${\lambda_x}={\lambda_{U{O_2}}}$$ unknown conductivity of UO2 $${\lambda_s}$$ = known thermal conductivity of secondary standard

Understanding and predicting behavior in organizations requires a consideration of person and situation factors, and how these factors interact. This paper develops and longitudinally tests a model...

This paper introduces survival analysis, a set of powerful statistical techniques which are useful in turnover research and other behavioral studies with a binary dependent variable and observation...

This paper introduces a categorical data analysis technique called Hildebrand's del. The advantages of del are; it allows for the testing of customized prediction rules, it provides a strength of a...

This paper describes some results from a four year longitudinal research study of Canadian government controlled corporations engaged in business activities. It summarizes findings with respect to ...

This paper reports a five-year longitudinal study of the management selection and allocation process in a specific, industrial R&D laboratory. Predictors included intelligence measures, interest pa...

This is the first of a series of papers designed to report the various stages of a longitudinal research project on the study of managerial effectiveness. The purposes of this article are: (1) to s...

This paper presents some ideas which may lead toward an analytic framework for the internal analysis of the context, structure and performance of complex organizations. Such a framework is needed to guide longitudinal research on organizations and in systematically gaining scientific knowledge on the internal functioning of organizations over time. Based on a set of premises, a theoretical model for organization assessment is developed.

This paper presents a theory on how and why pair-wise inter-agency relationships emerge and how they function over time by developing six hypotheses. The hypotheses are derived from six premises ab...

This paper highlights a number of issues concerning the measurement of managerial role behavior. A methodology for assessing and validating measures of managerial role behavior is described and illustrated by means of a longitudinal study. The results suggest the power of the type of task a manager accepts in ordering a manager's role behavior and his superior's expectations. The implication of the study is that research attention should not only be focused upon theoretical constructs, but also upon understanding the concrete behavior setting in which theoretical constructs are examined.

One of the major factors which deter mines the validity of research findings is undoubtedly the effectiveness of the decision-making process in setting up a design and a general methodology which are both rigorous and compatible with the aims of the study. Indeed, all the decisions made, be they major or minor ones, and related problems, vary from one study to the next depending largely on the nature and purpose of the exercise. The great majority of decisions required in designing a study are made in its early stages, It is usually the case, however, that in the course of a study other decisions would have to be taken. Since most decisions are interrelated, a change in one would precipitate a change in, or a reconsideration of, at least a second decision. Vis-a-vis the above, it is the purpose of this paper to discuss some of the aspects and issues which should be considered in a research study of the relationship between teaching and attainment. Although most of the following arguments and considerations would be valid for such a study at the primary or secondary level of education, these would be more true at the former level., peer-reviewed

The article presents a discussion of the costs and benefits of affiliation of business firms to business groups (BGs). Research examining the role of BGs on the internationalization of affiliate fi...