Search

For the functional linear models in which the dependent variable is functional and the predictors are scalar, robust regularization for simultaneous variable selection and regression parameter estimation is an important yet challenging issue. In this paper, we propose two types of regularized robust estimation methods. The first estimator adopts the ideas of reproducing kernel Hilbert space, least absolute deviation and group Lasso techniques. Based on the first method, the second estimator applies the pre-whitening technique and estimates the error covariance function by using functional principal component analysis. Simulation studies are conducted to examine the performance of the proposed methods in small sample sizes. The method is also applied to the Canadian weather data set, which consists of the daily average temperature and precipitation observed by 35 meteorological stations across Canada from 1960 to 1994. Numerical simulations and real data analysis show a good performance of the proposed robust methods for function-on-scalar models. [ABSTRACT FROM AUTHOR]

Turning movements are one of the key inputs required for several traffic studies. Several methods have been developed to measure them. However, present techniques have high operational or capital costs, which motivate researchers to develop new techniques to estimate turning movements. However, there is neither a flexible technique available to make best use of different available information types, nor a framework that supports deciding additional data to achieve a target accuracy. This paper proposes a new methodology using all available data to identify the subspace containing all solutions and determine its centroid; thus, providing the most realistic and non-extreme solution. In addition, a framework, including scenarios with different data combinations, is developed with capability to evaluate the proposed solution and then locate further measurements to achieve the target accuracy. The framework is validated using a considerable set of intersections at Edmonton city, Canada. The results show that the proposed framework can achieve the target accuracy with minimum field measurements saving time, effort and cost. [ABSTRACT FROM AUTHOR]

In Canada, an employee dismissed without just cause--defined to include layoffs for lack of work as well as dismissals without sufficient grounds--can sue the employer for a severance payment in lieu of "reasonable notice." Because the court determines reasonable notice according to the circumstances in each case, employers cannot easily calculate the correct amount of severance to give employees. The authors of this study identify the factors that significantly affected the length of notice awarded in more than 100 British Columbia cases in 1980-86 and develop a regression-based algorithm to estimate reasonable notice. They find that seven predictors account for 69 percent of the variance in reasonable notice awards. A test of the model with Canada-wide data shows it to be highly generalizable to other wrongful dismissal cases in Canada. [ABSTRACT FROM AUTHOR]

This study discusses the construction of a high-resolution ensemble Kalman filter system (the HREnKF) developed for the Marine Environmental Observation Prediction and Response (MEOPAR) network. The HREnKFruns at a horizontal resolution of 2.5 km and is intended to provide forecasts at lead times up to 12 h. This system was adapted from the global EnKF system in operation at Environment and Climate Change Canada. As a first development step, only the most necessary modifications have been implemented. The changes include an hourly cycling frequency, smaller localization radii, and the explicit representation of microphysical processes. To assess its performance and orient future developments, the HREnKF was continuously cycled for a period of 12 days. Verification against surface observations reveals that the skill of the forecasts initialized from the HREnKF is comparable to that of control forecasts also integrated at a resolution of 2.5 km. A key component of this study is the comparison of correlation estimated from ensembles at resolutions of 2.5, 15, and 50 km. At 2.5 km, correlation lengths are smaller than those found at 15 and 50 km. These short correlation lengths demand a high observational density, which is not available over the west coast domain where the HREnKF was tested. The spatial and temporal variability of the correlations is also assessed for the HREnKF system. It is found that correlation patterns are complex and do not generally decrease monotonically away from the reference point around which they are estimated. This result is important as it indicates that separation distance may not be the ideal parameter to use as a basis for localization strategies. [ABSTRACT FROM AUTHOR]

In this note a distributed lag model is employed to analyze the flow of capital in outstanding issues of Canadian stocks between Canada and the United States. It is proposed that the movement of such capital reflects, to a large extent, changes in the relative earnings yield on stocks in the two markets. To analyze this flow, the following hypothesis is considered: (1) S[sub t] = α + β E[sub t][sup *] + u[sub t] where S[sub t] represents capital flows in outstanding Canadian common and preferred shares, and E[sub t][sup *] is the expected form of E[sub t], the relative earnings yield. E[sub t] is defined here as (2) E[sub t] = ([sup e]/p)[sub c]/([sup e]/p)[sub us] where ([sup e]/p)[sub c]and ([sup e]/p)[sub us] are the reciprocals of the price-earnings ratio for Canadian and American stocks respectively. Since E[sub t][sup *] is unknown, it has to be related to observables. For this purpose the following hypothesis is assumed for the formation of stock market expectations: (3) E[sub t][sup *] = E[sub t-1][sup *] = (1 - γ) (E[sub t] - E[sub t-1][sup *]). [ABSTRACT FROM AUTHOR]

Scientific collaboration is one of the important drivers of research progress that supports researchers in the generation of novel ideas. Collaboration networks and their impact on scientific activities thus already attracted some attention in the research community, but no work so far studied possible factors which can influence the network positions of the researchers at the individual level. The objective of this paper is to investigate various characteristics and roles of the researchers occupying important positions in the collaboration network. For this purpose, we focus on the collaboration network among Canadian researchers during the period of 1996 to 2010 and employ multiple regression models to estimate the impact on network structure variables. Results highlight the crucial role of past productivity of the researchers along with their available funding in determining and improving their position in the co-authorship network. It is shown that researchers who have great influence on their local community do not necessarily publish high quality works. We also find that highly productive researchers not only have more important connections but also play a critical role in connecting other researchers. Moreover, although mid-career scientists tend to collaborate more in knit groups and on average have higher influence on their local community, our results specifically highlight the important role of young researchers who occupy mediatory positions in the network which enable them to connect different communities and fuel information transmission through the network. [ABSTRACT FROM AUTHOR]

A model-FUNNEL-GHG-OS ( FUN damental E N gineering Principl E s- based Mode L for Estimation of G reen H ouse G ases in the O il S ands) based on fundamental engineering principles was developed to estimate the specific energy consumption and GHGs (greenhouse gas emissions) for upgrading bitumen to produce SCO (synthetic crude oil). The model estimates quantity of SCO produced, the consumption of hydrogen, steam, natural gas and power in two different upgrading operations, namely delayed coking and hydroconversion. Hydroconversion upgrading is more energy and GHG (433.4 kgCO 2 eq/m 3 of bitumen) intensive than delayed coker upgrading (240.3 kgCO 2 eq/m 3 of bitumen) but obtains a higher yield of SCO. This research explores bitumen pathways in oil sands – upgrading bitumen to SCO, followed by transporting and refining SCO as compared to transporting and refining dilbit. The energy consumption, GHG emissions and volume of transportation fuels obtained from refining of different oil sands feeds has been investigated. Refining of oil sands products produce 7.9 to 15.72 gCO 2 eq per MJ of refined product. Refining of SCO to transportation fuels produces 41% and 49% less emissions than dilbit and bitumen respectively. [ABSTRACT FROM AUTHOR]

A qualitative techniques of poverty estimation is needed to better implement, monitor and determine national areas where support is most required. The problem of small area estimation (SAE) is the production of reliable estimates in areas with small samples. The precision of estimates in strata deteriorates (i.e. the precision decreases when the standard deviation increases), if the sample size is smaller. In these cases traditional direct estimators may be not precise and therefore pointless. Currently there are many indirect methods for SAE. The purpose of this paper is to analyze several different types of techniques which produce small area estimates of poverty. [ABSTRACT FROM AUTHOR]

Missing covariate data are common in biomedical studies. In this paper, we propose a reweighting method to estimate the regression parameters in the additive hazards regression model when some of the covariates are missing at random. The resulting estimators are shown to be consistent and asymptotically normal. In addition, a lack-of-fit test is presented to assess the adequacy of the model with missing covariates. Simulation studies show that the proposed reweighting estimators perform well, and are more efficient than the weighted estimators for the missing covariate effects when the selection probability is small. An application to the mouse leukaemia data is provided. The Canadian Journal of Statistics 42: 285-307; 2014 © 2014 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Abstract: Background: Given the recent international debates about the effectiveness and appropriate age setpoints for legislated minimum legal drinking ages (MLDAs), the current study estimates the impact of Canadian MLDAs on mortality among young adults. Currently, the MLDA is 18 years in Alberta, Manitoba and Québec, and 19 years in the rest of Canada. Methods: Using a regression-discontinuity approach, we estimated the impacts of the MLDAs on mortality from 1980 to 2009 among 16- to 22-year-olds in Canada. Results: In provinces with an MLDA of 18 years, young men slightly older than the MLDA had significant and abrupt increases in all-cause mortality (14.2%, p =0.002), primarily due to deaths from a broad class of injuries [excluding motor vehicle accidents (MVAs)] (16.2%, p =0.008), as well as fatalities due to MVAs (12.7%, p =0.038). In provinces/territories with an MLDA of 19 years, significant jumps appeared immediately after the MLDA among males in all-cause mortality (7.2%, p =0.003), including injuries from external causes (10.4%, p <0.001) and MVAs (15.3%, p <0.001). Among females, there were some increases in mortality following the MLDA, but these jumps were statistically non-significant. Conclusions: Canadian drinking-age legislation has a powerful impact on youth mortality. Given that removal of MLDA restrictions was associated with sharp upturns in fatalities among young men, the MLDA likely reduces population-level mortality among male youth under the constraints of drinking-age legislation. Alcohol-control policies should target the transition across the MLDA as a pronounced period of mortality risk, especially among males. [Copyright &y& Elsevier]

We propose a nonparametric method to assess the effects of one or more covariates on the cure rate for survival data with a cure fraction. The method extends the existing work on single sample and multiple sample cases and also allows for a continuous covariate. The proposed estimator is shown to be consistent and asymptotically normal. A simulation study shows that the proposed method estimates the covariate effect on cure rate with smaller biases than the existing semi-parametric cure models, particularly when the semi-parametric cure models mis-specify the effect. The proposed method is applied to a study for leukaemia patients to assess the effect of age on the chance of being cured after bone marrow transplantation. The Canadian Journal of Statistics 42: 1-17; 2014 © 2013 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Item non-response in sample surveys is usually addressed by imputation. A bootstrap method that treats the imputed values as if they were observed generally leads to variance estimates that are too small. Shao & Sitter (1996) introduced a bootstrap method in this context, which leads to consistent variance estimators when the sampling fraction is small. In the context of stratified simple random sampling, we introduce the independent bootstrap, which is valid even when the sampling fraction is large. It consists of modifying a bootstrap method for sample surveys, of independently generating the response status of each unit, and of imputing the non-respondents in the bootstrap sample. We pay special attention to the bootstrap survey weights approach of Rao, Wu, & Yue (1992). The Canadian Journal of Statistics 42: 142-167; 2014 © 2014 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

The present article describes the current research focus and the future research trends associated with investigating emissions from naturally ventilated buildings as identified at the technical session entitled “Emission from naturally ventilated buildings (Measurement, modelling, reduction and assessment)”, that was held during the International Commission of Agricultural and Biosystems Engineering (Commission Internationale du Genie Rural, CIGR) World Congress in Quebec, Canada, between the 13th and 18th June 2010. Current knowledge and measurement techniques can only provide reasonable estimates of emissions from naturally ventilated livestock buildings. Thus, further research and development are required. The goal is a point where measurements are precise enough to validate simulation models and to obtain more consistent and accurate emission estimates. To achieve this, better synergy between mathematical modelling, physical modelling and field measurements of ventilation rates in naturally ventilated livestock buildings is required. The review of research presented at the Quebec meeting identified the following intermediate goals: 1. Investigate and determine error sources and measurement inaccuracies. Error analysis might be necessary to interpret results and establish research priorities. 2. Develop intelligent ventilation control systems that can handle highly fluctuating ventilation conditions in naturally ventilated livestock buildings. 3. Develop practical field methods that can be used as reference standards. 4. Establish a dedicated facility that could be used to obtain precise reference measurements of ventilation rates in naturally ventilated building. To enable this, a parallel development of new technologies (instrumentation and methodology) is required. [Copyright &y& Elsevier]

Highlights: [•] This paper aims at estimating the effect of implementing a commuter train service. [•] A difference-in-differences estimator is proposed to capture the proximity effect. [•] The overall market premium on mean house price is estimated to be 2.6%. [•] The premium generate a yearly fiscal increase of revenue of 11 million dollars. [Copyright &y& Elsevier]

This paper uses a computable general equilibrium model to assess the welfare cost of changing the method of water allocation in Canada towards one that uses prices to ration demand. We model the introduction of a price on both water that is abstracted as well as water that is consumed (that is abstracted, and not returned to the source). We estimate that reducing water consumption by 25 % would require imposition of a price on water consumption of around $$\$0.21/\text{ m }^{3}$$. Similarly, introduction of a water abstraction charge of about $$\$0.013/\text{ m }^{3}$$ would be sufficient to reduce water abstraction by 25 %. We find that if revenues from water pricing are returned in lump sum to households, the introduction of water pricing would result in a modest welfare loss. When revenues from water pricing are used to offset existing taxes, we find a gain in welfare corresponding to a 'strong double dividend.' [ABSTRACT FROM AUTHOR]

New estimates of production of sub-ice and ice microalgae in the shelf seas of the Canadian Arctic and in the Canada Basin of the Arctic Ocean derived from reduction of nitrates in the water column, as recorded in time series available in publicly held data bases, suggest that it is of greater magnitude (up to 30 g C m year) and represent a higher proportion (up to 50 % on the shelf and 90 % in the Canada Basin) of net community production than previously estimated for both areas. [ABSTRACT FROM AUTHOR]

There is a common misconception among government officials that environmental regulations are bad for economic growth. Citing economic reasons, the Canadian federal government passed legislation in 2012 restricting the length of environmental reviews of new developments, even though review times were not empirically known. Using annual reports to Parliament from 2001 to 2010, we estimated using time-series analyses that review times under the Fisheries Act conformed to the new government mandated review times prior to major legislative changes to federal environmental oversight. The majority of submissions were processed within 1 year for mitigated impacts and within 2 years for authorized impacts. While it is possible that a minority of projects take longer, there is no evidence of large backlogs in the review process, and Canadian review times appear quicker than those in the United States. We highlight the need for empirical estimates of the costs of environmental regulations before governments enact substantial legislative changes that reduce environmental oversight and offer alternate recommendations for expediting environmental review times. [ABSTRACT FROM AUTHOR]

Background: Fetal Alcohol Spectrum Disorder (FASD) is underdiagnosed in Canada. The diagnosis of FASD is not simple and currently, the recommendation is that a comprehensive, multidisciplinary assessment of the individual be done. The purpose of this study was to estimate the annual cost of FASD diagnosis on Canadian society. Methods: The diagnostic process breakdown was based on recommendations from the Fetal Alcohol Spectrum Disorder Canadian Guidelines for Diagnosis. The per person cost of diagnosis was calculated based on the number of hours (estimated based on expert opinion) required by each specialist involved in the diagnostic process. The average rate per hour for each respective specialist was estimated based on hourly costs across Canada. Based on the existing clinical capacity of all FASD multidisciplinary clinics in Canada, obtained from the 2005 and 2011 surveys conducted by the Canada Northwest FASD Research Network, the number of FASD cases diagnosed per year in Canada was estimated. The per person cost of FASD diagnosis was then applied to the number of cases diagnosed per year in Canada in order to calculated the overall annual cost. Results: Using the most conservative approach, it was estimated that an FASD evaluation requires 32 to 47 hours for one individual to be screened, referred, admitted, and diagnosed with an FASD diagnosis, which results in a total cost of $3,110 to $4,570 per person. The total cost of FASD diagnostic services in Canada ranges from $3.6 to $5.2 million (lower estimate), up to $5.0 to $7.3 million (upper estimate) per year. Discussion: As a result of using the most conservative approach, the cost of FASD diagnostic services presented in the current study is most likely underestimated. The reasons for this likelihood and the limitations of the study are discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the sensitivity of demand for air travel by singleton passengers, couples, and families. It examines how the demand for air travel by these groups is potentially different. In this study, a compound Poisson structure of the demand of different passenger groups is considered, and aggregate demand observations and maximum likelihood procedures are used to decompound the processes and estimate demand sensitivity of each group of customers to price, time, season, and the economic cycle. The methodology is applied to Canadian market data and the results indicate there are significant differences among the different groups of customers. [Copyright &y& Elsevier]

Abstract: Chicken eggs from five different production types (conventional, omega-3 enriched, free range, organic and free run) were collected, when available, from three regions (west, central and east) of Canada to determine persistent organic pollutant (POP) concentrations. Total polychlorinated biphenyl (PCB) concentrations (∑37 congeners) in yolks from the eggs ranged from 0.162ngg−1 lipid to 24.8ngg−1 lipid (median 1.25ngg−1 lipid) while the concentration of the sum of the 6 indicator PCBs ranged from 0.100ngg−1 lipid to 9.33ngg−1 lipid (median 0.495ngg−1 lipid). Total polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) concentrations ranged from 2.37pgg−1 lipid to 382pgg−1 lipid (median 9.53pgg−1 lipid). The 2005 WHO toxic equivalency (TEQ) ranged from 0.089pg TEQPCDD/F+dioxin-like[DL]-PCB g−1 lipid to 12.8pg TEQPCDD/F+DL-PCB g−1 lipid (median 0.342pg TEQPCDD/F+DL-PCB g−1 lipid). PCB and PCDD/F concentrations were significantly different (p <0.001) in egg yolks from different regions of collection. In contrast to observations in Europe, PCB and PCDD/F concentrations in Canadian egg yolks were not impacted solely by the production type (e.g., conventional, free range, organic, etc.) used to maintain the laying chickens. Additionally, only one Canadian free range yolk from western Canada (12.8pg TEQPCDD/F+DL-PCB g−1 lipid) exceeded the European toxic equivalent concentration limits for eggs (5pg TEQPCDD/F+DL-PCB g−1 lipid). This differs from observations in Europe where free range/home produced eggs frequently have higher POP concentrations than eggs from other production types. Median PCB dietary intake estimates based on consumption of eggs were less than 10ngd−1 while median PCDD/F intakes were less than 45pgd−1. [Copyright &y& Elsevier]

Food allergies are newly emerging health risks, and some evidence indicates that their prevalence is increasing. Public perception, however, is that the prevalence of food allergies is much greater than systematic estimates suggest. As food allergies increasingly permeate everyday life, this paper explores how associated risks are constructed through the mass media. In particular, nine years of media coverage of food allergies are analysed through the lens of issue framing and claims-making. Results show that advocates and affected individuals dominate discussions around policy action, while researchers and health professionals are diagnosing the causes of food allergy. Results also suggest that there is competition over the definition of food allergies, which may, in turn, be shaping public understanding of the related risks. There is also an indication that the framing of food allergies is evolving over time, and that the discussion is becoming increasingly one-sided with affected individuals leading the charge. [ABSTRACT FROM AUTHOR]

Coarse data is a general type of incomplete data that includes grouped data, censored data, and missing data. The likelihood-based estimation approach with coarse data is challenging because the likelihood function is in integral form. The Monte Carlo EM algorithm of Wei & Tanner [Wei & Tanner (1990). Journal of the American Statistical Association, 85, 699-704] is adapted to compute the maximum likelihood estimator in the presence of coarse data. Stochastic coarse data is also covered and the computation can be implemented using the parametric fractional imputation method proposed by Kim [Kim (2011). Biometrika, 98, 119-132]. Results from a limited simulation study are presented. The proposed method is also applied to the Korean Longitudinal Study of Aging (KLoSA). The Canadian Journal of Statistics 40: 604-618; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

In medical diagnostic testing problems, the covariate adjusted receiver operating characteristic (ROC) curves have been discussed recently for achieving the best separation between disease and control. Due to various restrictions such as cost, the availability of patients, and ethical issues quite frequently only limited information is available. As a result, we are unlikely to have a large enough overall sample size to support reliable direct estimations of ROCs for all the underlying covariates of interest. For example, some genetic factors are less commonly observable compared with others. To get an accurate covariate adjusted ROC estimation, novel statistical methods are needed to effectively utilize the limited information. Therefore, it is desirable to use indirect estimates that borrow strength by employing values of the variables of interest from neighbouring covariates. In this paper we discuss two semiparametric exponential tilting models, where the density functions from different covariate levels share a common baseline density, and the parameters in the exponential tilting component reflect the difference among the covariates. With the proposed models, the estimated covariate adjusted ROC is much smoother and more efficient than the nonparametric counterpart without borrowing information from neighbouring covariates. A simulation study and a real data application are reported. The Canadian Journal of Statistics 40: 569-587; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

We show that the maximum likelihood estimators (MLEs) of the fixed effects and within-cluster correlation are consistent in a heteroscedastic nested-error regression (HNER) model with completely unknown within-cluster variances under mild conditions. The result implies that the empirical best linear unbiased prediction (EBLUP) method for small area estimation is valid in such a case. We also show that ignoring the heteroscedasticity can lead to inconsistent estimation of the within-cluster correlation and inferior predictive performance. A jackknife measure of uncertainty for the EBLUP is developed under the HNER model. Simulation studies are carried out to investigate the finite-sample performance of the EBLUP and MLE under the HNER model, with comparisons to those under the nested-error regression model in various situations, as well as that of the jackknife measure of uncertainty. The well-known Iowa crops data is used for illustration. The Canadian Journal of Statistics 40: 588-603; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Clinical trials usually involve efficient and ethical objectives such as maximizing the power and minimizing the total failure number. Interim analysis is now a standard technique in practice to achieve these objectives. Randomized urn models have been extensively studied in the literature. In this paper, we propose to perform interim analysis on clinical trials based on urn models and study its properties. We show that the urn composition, allocation of patients and parameter estimators can be approximated by a joint Gaussian process. Consequently, sequential test statistics of the proposed procedure converge to a Brownian motion in distribution and the sequential test statistics asymptotically satisfy the canonical joint distribution defined in Jennison & Turnbull (Jennison & Turnbull 2000. Group Sequential Methods with Applications to Clinical Trials, Chapman and Hall/CRC). These results provide a solid foundation and open a door to perform the interim analysis on randomized clinical trials with urn models in practice. Furthermore, we demonstrate our proposal through examples and simulations by applying sequential monitoring and stochastic curtailment techniques. The Canadian Journal of Statistics 40: 550-568; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Recurrent event data arise commonly in medical and public health studies. The analysis of such data has received extensive research attention and various methods have been developed in the literature. Depending on the focus of scientific interest, the methods may be broadly classified as intensity-based counting process methods, mean function-based estimating equation methods, and the analysis of times to events or times between events. These methods and models cover a wide variety of practical applications. However, there is a critical assumption underlying those methods-variables need to be correctly measured. Unfortunately, this assumption is frequently violated in practice. It is quite common that some covariates are subject to measurement error. It is well known that covariate measurement error can substantially distort inference results if it is not properly taken into account. In the literature, there has been extensive research concerning measurement error problems in various settings. However, with recurrent events, there is little discussion on this topic. It is the objective of this paper to address this important issue. In this paper, we develop inferential methods which account for measurement error in covariates for models with multiplicative intensity functions or rate functions. Both likelihood-based inference and robust inference based on estimating equations are discussed. The Canadian Journal of Statistics 40: 530-549; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Modelling for marked point processes is an important problem, but has received remarkably little attention in the statistical literature. The authors developed a marked point process model that incorporates the use of functional data analysis in a joint estimation of the frequency function of the point process and the intensity of the mark, with application to data from 22 lupus patients consisting of times of flares in symptom severity combined with a quantitative assessment of the severity. The data indicate that a rapid decrease in drug dose is significantly associated with a decrease in flare frequency. Experiments with simulated data designed to model the actual data further support this conclusion. The Canadian Journal of Statistics 40: 517-529; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Abstract: For the past decades, gas hydrate reservoirs have beneficiated from an increasing attention in the academic and industrial worlds. As a result, there is a growing need to develop specific and comprehensive gas hydrate reservoir characterization methods. This study explores the use of a stochastic Bayesian algorithm to integrate well-logs and 3D acoustic impedance in order to estimate gas hydrate grades (product of saturation and total porosity) over a representative volume of the Mallik gas hydrate field, located in the Mackenzie Delta, Northwest Territories of Canada. First, collocated log data from boreholes Mallik 5L-38 and 2L-38 are used to estimate the statistical relationship between acoustic impedance and gas hydrate grades. Second, conventional stochastic Bayesian simulation is applied to generate multiple gas hydrate grade 3D fields integrating log data and lateral variability of 3D acoustic impedance. These equiprobable scenarios permit to quantify the uncertainty over the estimation, and identify zones where this uncertainty is greater. Contrary to conventional stochastic reservoir modeling workflows, the proposed method allows integrating non Gaussian and non linear distributions. This permits to handle bimodal distributions without using complex stochastic transforms. The results present gas hydrate grade values that are in accordance with well-log data. The relatively low standard deviation calculated at each pixel using all realizations suggests that gas hydrate grades is well explained by acoustic impedance and log data. [Copyright &y& Elsevier]

SUMMARY We derive a quantity-based structural gravity equation system in which both trade flows and error terms are cross-sectionally correlated. This system can be estimated using techniques borrowed from the spatial econometrics literature. To illustrate our methodology, we apply it to a well-known Canada-US trade dataset. We find that border effects between the USA and Canada are smaller than suggested by previous studies: about 7.5 for Canadian provinces and about 1.3 for US states. Hence controlling directly for cross-sectional interdependence among both trade flows and error terms reduces measured border effects by capturing 'multilateral resistance'. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Near infrared reflectance spectroscopy (NIRS) holds promise for rapid assessment of soil total N and organic C contents, but its ability to predict soil N supply in soils with contrasting physio-chemical properties needs to be evaluated. The objectives of this study were to: (i) evaluate NIRS predictions of measured soil parameters (total N, organic C, and C/N ratio) and as an indirect indicator of soil N supply, namely corn (Zea mays L.) N uptake and (ii) assess the effect of sample set heterogeneity on NIRS predictions. Soil samples (n = 282 in the total set) were collected between 2000 and 2009 from 52 sites across four Canadian provinces and were allocated to fine- (≥ 350 g clay kg-1 n = 101) and coarse-textured subsets (<350 g clay kg-1 n = 181). Prediction models were developed using modified partial least squares regression. Prediction precision was assessed using the coefficient of determination (R²) and ratio of prediction to deviation (RPD = ratio of standard error of prediction corrected for bias to standard deviation of the reference data used in the validation). For the total set, predictions were reliable for total N, organic C and C/N ratio (0.7 ≤ R² ≤ 0.9, 1.75 ≤ RPD ≤ 3), and less reliable for soil N supply (R² < 0.7, RPD < 1.75). Prediction precision for total N, organic C, C/N ratio, and soil N supply increased with set homogeneity (i.e., better in the texture subsets than the total set), resulting in reliable predictions for soil N supply (RPD ≥ 2.00) in the texture subsets. This study demonstrated the possibility of developing reliable NIRS predictive models for total N, organic C, and C/N ratio for soils with contrasting physio- chemical properties, as well as reliable NIRS predictive models for soil N supply within homogeneous texture sets. [ABSTRACT FROM AUTHOR]

Two internet-based surveys were conducted with adults aged 35 to 84-885 respondents in the United States and 641 respondents in Canada-to estimate willingness to pay (WTP) for reducing mortality risks through out-of-pocket costs for health-care programs. All respondents were asked a series of choice questions followed by a payment-card question. Causes of death included cancer and heart attack. Levels of annual mortality-risk reduction were 1, 2, and 5 in 10,000. Converted to values of statistical life, results were in the range of $4-5 million (2002 U.S. dollars) for the choice-question results for a 2-in-10,000 annual risk reduction for illness-related mortality. U.S. and Canadian results were similar. The payment-card results were about 50% lower than the choice-question results. WTP to reduce mortality risk was essentially the same for cancer and heart attack. The results showed WTP weakly increasing with age, and no evidence of lower WTP for older adults versus middle-aged adults. ( JEL Q51) [ABSTRACT FROM AUTHOR]

This article provides robust estimates that the Bank of Canada, Bank of England, Federal Reserve Bank and the European Central Bank (ECB) respond to a 1% increase in oil price expectations with an increase in the interest rate of on average about 11 basis points. To correctly assess the information set of a central bank we use private sector forecasts and disentangle oil price expectations from inflation expectations. We also find asymmetries in the central bank's behaviour and report that those central banks do not respond to the realized oil price. [ABSTRACT FROM AUTHOR]

Abstract: Traditional geostatistical modelling of orebodies and estimation of grade–tonnage curves do not account for the uncertainty of the orebody grades and tonnages. Geological interpretations of complex shapes are often over-constrained, and therefore do not properly identify the location of the ore. In these situations, tonnage is often under-estimated and grade is over-estimated, resulting in orebody models used for mine planning that lead to costly financial decisions. This paper presents an approach aiming to better assess the uncertainty in an orebody model. The approach is applied to Vale''s West Orebody of the Coleman McCreedy Mine, a poly-metallic deposit containing nickel, copper, gold, platinum and palladium. To encapsulate the orebody''s variability and uncertainty, the nickel–copper sulphide mineralized zone is simulated using the single normal equation simulation method. The realizations serve as the orebody models from which the grades of multiple elements are jointly simulated using Min/Max Autocorrelation Factors. The final result is a series of equiprobable representations of the mineralization that incorporates both grade and tonnage uncertainty. The case study indicates that had conventional orebody estimations been used, there would have been a 10% over-estimation of orebody volume, along with significant over-estimation of low-grade material and under-estimation of high-grade material. [Copyright &y& Elsevier]

In this paper we consider weighted generalized-signed-rank estimators of nonlinear regression coefficients. The generalization allows us to include popular estimators such as the least squares and least absolute deviations estimators but by itself does not give bounded influence estimators. Adding weights results in estimators with bounded influence function. We establish conditions needed for the consistency and asymptotic normality of the proposed estimator and discuss how weight functions can be chosen to achieve bounded influence function of the estimator. Real life examples and Monte Carlo simulation experiments demonstrate the robustness and efficiency of the proposed estimator. An example shows that the weighted signed-rank estimator can be useful to detect outliers in nonlinear regression. The Canadian Journal of Statistics 40: 172-189; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

It is known that the profile empirical likelihood method based on estimating equations is computationally intensive when the number of nuisance parameters is large. Recently, Li, Peng, & Qi (2011) proposed a jackknife empirical likelihood method for constructing confidence regions for the parameters of interest by estimating the nuisance parameters separately. However, when the estimators for the nuisance parameters have no explicit formula, the computation of the jackknife empirical likelihood method is still intensive. In this paper, an approximate jackknife empirical likelihood method is proposed to reduce the computation in the jackknife empirical likelihood method when the nuisance parameters cannot be estimated explicitly. A simulation study confirms the advantage of the new method. The Canadian Journal of Statistics 40: 110-123; 2012 © 2012 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The mapping of the small hydropower (SHP) resource over a given territory is indispensable to identify suitable sites for the development of SHP renewable energy projects. In this study, a straightforward method to map the SHP potential over a large territory is presented. The methodology uses a synthetic hydro network (SHN) created from digital elevation models (DEM) to ensure precise hydro head estimations. From the SHN, hydro heads are calculated by subtracting the minimum from the maximum elevation of synthetic stream segments. Subsequently, stream segments with low hydro heads over a specified maximum distance are removed. Finally, the method uses regional regression models to estimate the annual baseflow for all drainage areas in the study area. The technical SHP potential can then be estimated as a function of the hydro head and maximum penstock length. An application of the method is made to the province of New Brunswick, Canada, where SHP maps have been developed to promote the development of the SHP energy sector in the province. In terms of the SHP opportunity, it is shown that the province of New Brunswick (71,450km2) has a good SHP resource. Using a representative hydro head (10m) and penstock length (3000m) for the region, 696 potential sites have been identified over the territory. Results show that the technical SHP potential for New Brunswick is 368MW for the conventional hydroelectric reservoir SHP configuration, while for the run-of-river SHP configuration, the technical SHP potential is 58MW. [Copyright &y& Elsevier]

Objectives: The goal of this study was to analyze health-related quality of life (HRQL) data from a Canadian population with type 2 diabetes in order to estimate the disutility associated with experiencing a diabetes-related complication. Methods: The EQ-5D, a standardized instrument for use as a measure of health outcome, was administered to 1,147 patients in Hamilton, Ontario, with type 2 diabetes. After controlling for age, gender, and duration of diabetes, changes in utility values were estimated by regressing the EQ-5D scores onto binary indicators for the presence of an event. The primary method of analysis was Ordinary Least Squares (OLS) and due to concerns over non-Normality, bootstrap standard errors (SE) were calculated. Results: The analysis included 1,143 participants. Based on the OLS model, reductions in HRQL were associated with duration of diabetes (−0.0015, SE = 0.0006), experiencing a myocardial infarction (MI) (−0.059, SE = 0.017), amputation (−0.063, SE = 0.059), stroke (−0.046, SE = 0.023), and kidney failure (−0.102, SE = 0.047). Conclusion: This study estimated the reductions in HRQL associated with several important complications commonly experienced in patients with diabetes. The greatest impacts on HRQL were associated with kidney failure and MI. The utility values calculated here can be used to assess the outcome of interventions that reduce these diabetes-related complications and will have a useful impact on future economic evaluations of diabetes management strategies in Canada. [ABSTRACT FROM AUTHOR]

To help engineers calculate design seismic loads, the 2005 edition of the National Building Code of Canada provides empirical equations to estimate the fundamental lateral period of a building. Unfortunately, these equations are inaccurate, so the fundamental period of a building once it is erected could be considerably different than the period used in design. In this study, we use experimental period data and uncertainty propagation to show that the uncertainty associated with the fundamental period significantly influences the accuracy of design seismic loads. When the period from the appropriate empirical equation is used in design, base shear may be considerably overestimated; while it may be considerably underestimated when the maximum period allowed by the code is used. Further, we show that the resulting uncertainty in base shear varies with location, seismic force-resisting system, site conditions, and building height. [ABSTRACT FROM AUTHOR]

Abstract: Energy companies can adjust the estimation of their reserves. We investigate how these revisions impact on the value of these firms. We analyze 100 revisions in seventeen countries for the period 2000-2010. We use an event study and find that the revisions of energy reserves significantly impact on the market value of the firm. We also discover an asymmetry in this response as the market’s reaction to downward revisions is much larger than that to upward revisions. Furthermore, the response to revisions in Australia, Canada, UK and US is smaller than that in the other 13 countries and the response is smaller in the years with turmoil on the energy markets. [Copyright &y& Elsevier]

Abstract: This paper uses sequential stochastic dominance procedures to compare the joint distribution of health and income across space and time. It is the first application of which we are aware of methods to compare multidimensional distributions of income and health using procedures that are robust to aggregation techniques. The paper’s approach is more general than comparisons of health gradients and does not require the estimation of health equivalent incomes. We illustrate the approach by contrasting Canada and the US using comparable data. Canada dominates the US over the bottom part of the bi-dimensional distribution of health and income, though not generally over the uni-dimensional distributions of health or income. The paper also finds that welfare for both Canadians and Americans has not unambiguously improved during the last decade over the joint distribution of income and health, in spite of the fact that the uni-dimensional distributions of income have clearly improved during that period. [Copyright &y& Elsevier]

Abstract: Carbon capture and geological storage (CCS) operations will require an environmental risk analysis to determine, among other things, the risk that injected CO2 or displaced brine will leak from the injection formation into other parts of the subsurface or surface environments. Such an analysis requires site characterization including identification of potential leakage pathways. In North America, the century-long legacy of oil and gas exploration and production has left millions of oil and gas wells, many of which are co-located with otherwise good geological storage sites. Potential leakage along existing wells, coupled with layered stratigraphic sequences and highly uncertain parameters, makes quantitative analysis of leakage risk a significant computational challenge. However, new approaches to modeling CO2 injection, migration, and leakage allow for realistic scenarios to be simulated within a probabilistic framework. Using a specific field site in Alberta, Canada, we perform a range of computational studies aimed at risk analysis with a focus on CO2 and brine leakage along old wells. The specific calculations focus on the injection period, when risk of leakage is expected to be largest. Specifically, we simulate 50 years of injection of supercritical CO2 and use a Monte Carlo framework to analyze the overall system behavior. The simulations involve injection, migration, and leakage over the 50-year time horizon for domains of several thousand square kilometers having multiple layers in the sedimentary succession and several thousand old wells within the domain. Because we can perform each simulation in a few minutes of computer time, we can run tens of thousands of simulations and analyze the outputs in a probabilistic framework. We use these kinds of simulations to demonstrate the importance of residual brine saturations, the range of current options to quantify leaky well properties, and the impact of depth of injection and how it relates to leakage risk. [Copyright &y& Elsevier]

The objectives of this study were to estimate genetic parameters of milking temperament (MT) and milking speed (MS) in Canadian Holsteins and to examine associations of bull proofs of MT and MS with other economically important traits. First-lactation data consisted of 1,940,092 and 2,620,175 cows for MT and MS, respectively. Milking temperament and MS were recorded on a scale from 1 to 5 from very nervous to very calm and from very slow to very fast, respectively. The linear animal model included the fixed effects of herd-year-season of calving, stage of lactation, age at first calving, and the random effects of animal and residual. Both single-trait and bivariate analyses were carried out to estimate genetic parameters of MT and MS. For genetic parameter estimation, 20,000 records from randomly selected herds were used. However, for breeding value estimation, all records were included. Heritability values were 0.128 and 0.139 for MT and MS, respectively. The genetic correlation between MT and MS was 0.247. Analysis of bull proof correlation of MT and MS with other traits indicated that these traits were lowly correlated with a wide range of traits such as production, reproduction, conformation, and auxiliary traits. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to estimate the size and the growth of Quebec's underground economy, and the corresponding loss of taxes for the government. Our approach is based on a method developed by Pissarides and Weber (1989) and extended by Lyssiotou et al. (2004). The basic hypothesis is that individuals can under-report their earnings from self-employment but not from paid work, from which taxes are directly deducted. We estimate a consumer demand system in which the marginal propensity to consume is allowed to vary with the two types of earnings. We next estimate the amount of self-employment earnings that are under-reported. From this estimate, we calculate the relative size of the underground economy in Quebec. We use data from Statistics Canada's Survey of Household Spending. According to our results, Quebec's underground economy amounted to 4.6% of GDP in 1997 and increased slightly to 5.7% in 2002. For the government, this represents approximately $3.3 billion in forgone taxes for the year 2002. This estimate is very close to those reported by Gervais (1994) and Fortin and Lacroix (2009) using very different estimation methods and data. [ABSTRACT FROM AUTHOR]

Abstract: The impact of shipping noise on marine life and quality of marine mammal habitats in oceans and coastal environments has become a major concern worldwide. Background noise can also limits detection of marine mammal sounds in passive acoustic monitoring (PAM) systems. Characterisation of this noise over long time periods and estimates of the exposure of the different marine mammal groups are still very fragmentary and limited to only a few locations. This paper presents such observations for a part of a busy seaway of North America, the St. Lawrence Seaway, which cuts through the Gulf of St. Lawrence and crosses several cetaceans and pinnipeds feeding areas. Noise was continuously recorded for a 5-month period in summer 2005 by an AURAL autonomous hydrophone deployed close to the bottom in the 300-m deep seaway. The maximum received noise level in the 20Hz–0.9kHz band reached 136dB re 1μParms. The median level of 112dB re 1μParms was exceeded 50% of the time due to transiting merchant ships. Median spectral level tracks the reference curve for heavy traffic in oceans and 50% of the noise is within a ±6dB envelope around it. Strong spectral lines were common at low frequencies and in the 400–800Hz band. M-weighting functions applied for the three groups of cetaceans and pinnipeds indicate wideband median levels varying from 106 to 112dB-M re 1μParms surrounded by a ±5dB two-quartile interval. Higher values are expected for animals frequenting the sound channel at intermediate depths. As expected, the highest M-weighting levels correspond to low-frequency specialists and pinnipeds. Criteria for assessing the behavioural and physiological impacts of long term exposure of marine mammals to such shipping noise levels need to be worked out. [ABSTRACT FROM AUTHOR]

Some 353 isolated skulls and partial to complete skeletons with known locations have been collected in ~100 years from the 80 km2 of badlands in Dinosaur Provincial Park (DPP), Alberta, Canada. We wanted to estimate how many skeletons were lost to erosion before collection began and how many await discovery. Within the boundaries of DPP, a volume of rock 145 m thick between the surface of the down-cutting Red Deer River and the capping prairie was subdivided into 5 m thick slabs using digital elevation data with an average horizontal spatial resolution of 19 m and a vertical resolution of 1 m. The exposed surface area of each slab was calculated. Dinosaur fossil localities were determined with high-precision GPS surveys. The number of dinosaurs collected from the surface of a 5 m slab was divided by the product of the exposed area and an estimated erosional thickness of 80 cm to give a volume density of dinosaur fossils. Multiplying the volumes of rock lost from each layer by the dinosaur densities for each layer, the numbers of skeletons lost was determined. Estimates of the numbers of raisins in two loaves of raisin bread were made using a limited number of slices as a test of the method. Of the original volume of DPP, 6.58 km3 (60%) has eroded away, taking with it a mean number of 6310 hadrosaurs, 1640 ceratopsians, 1030 ankylosaurs, and 1600 theropods. The 5.02 km3 (40%) of rock remaining in the park can be expected to produce more dinosaur fossils of similar quality, with mean values of 6700 hadrosaurs, 1700 ceratopsians, 1010 ankylosaurs, and 1720 theropods. These estimates are minima as the estimation process excluded bone beds, the plethora of isolated bones littering the land surface of DPP, and the 100+ skulls and skeletons from the region that lack locality information. [ABSTRACT FROM AUTHOR]

Abstract: Dry spells, defined as extended periods of dry days, can serve as indicators of drought conditions, and are often used in the management of water resource systems, particularly for agriculture. In this study, the Canadian RCM (CRCM) projected changes to dry spell characteristics over Canada, for the April–September period, and their validation in current climate, are presented. Two CRCM integrations are considered; one validation integration for the 1961–2000 period and a transient climate change integration for the 1961–2100 period, corresponding to the SRES A2 scenario. The ability of the model to simulate dry spell characteristics, i.e. mean number of dry days, mean number of dry spells and selected return levels of maximum dry spell durations, and associated errors are assessed through comparison of integrations for the current 1971–2000 April–September period with those observed, derived from the observed precipitation records. Results suggest an underestimation of the mean number of dry days and 10- and 30-year return levels, while the model slightly overestimates the mean number of dry spells, at the grid-cell scale. Analysis of projected changes to dry spell characteristics for the future 2041–2070 and 2071–2100 periods, with respect to 1971–2000 period, suggests significant changes, particularly for the southern Prairies, where both mean number of dry days and return levels of maximum dry spell durations are projected to increase. Furthermore, combined analysis of changes to the amount of precipitation and mean number of dry days also suggests potential increase in drought conditions in future climates in this already drought-prone region for the April–September period. In addition to southern Prairies, this study also suggests significant changes to dry spell characteristics for other regions of Canada. [ABSTRACT FROM AUTHOR]

Summary: The onset date of positive water temperature in the annual thermal cycle of North-American streams is modeled using parametric (regression) and non-parametric (artificial neural networks) approaches. Physiographic, land cover and weather-related variables are used to predict the date of positive temperature onset for 191 station-years at 48 locations in Canada and in Northern US. Preliminary correlation analysis is performed in order to test the relationships between the physiographic/land cover/weather variables and the date of positive temperature onset. Moreover, several different subsets of variables are tested as inputs to each model type. Artificial neural networks can predict the date of positive temperature onset for a given station-year, given its longitude, lake coverage of its drainage basin, and two January–February daily temperature indices, with a split-sample validation root mean square error (RMSE) ∼8.8days. Ordinary least square (OLS) regression models allow to predict the onset date with RMSE ∼9.5days, given the station’s latitude, longitude, lake coverage and one January–February daily temperature index. OLS regression models adjusted on canonical variates combining 13 physiographic/land cover and weather variables achieve prediction performance ∼9.1days. The precipitation does not impact much on the onset date prediction for all tested models. [ABSTRACT FROM AUTHOR]