Order restricted inference for comparing the cumulative incidence of a competing risk over several populations

There is a substantial literature on testing for the equality of the cumulative incidence functions associated with one specific cause in a competing risks setting across several populations against specific or all alternatives. In this paper we propose an asymptotically distribution-free test when the alternative is that the incidence functions are linearly ordered, but not equal. The motivation stems from the fact that in many examples such a linear ordering seems reasonable intuitively and is borne out generally from empirical observations. These tests are more powerful when the ordering is justified. We also provide estimators of the incidence functions under this ordering constraint, derive their asymptotic properties for statistical inference purposes, and show improvements over the unrestricted estimators when the order restriction holds.Comment: Published in at http://dx.doi.org/10.1214/193940307000000040 the IMS Collections (http://www.imstat.org/publications/imscollections.htm) by the Institute of Mathematical Statistics (http://www.imstat.org

Estimation of extended mixed models using latent classes and latent processes: the R package lcmm

The R package lcmm provides a series of functions to estimate statistical models based on linear mixed model theory. It includes the estimation of mixed models and latent class mixed models for Gaussian longitudinal outcomes (hlme), curvilinear and ordinal univariate longitudinal outcomes (lcmm) and curvilinear multivariate outcomes (multlcmm), as well as joint latent class mixed models (Jointlcmm) for a (Gaussian or curvilinear) longitudinal outcome and a time-to-event that can be possibly left-truncated right-censored and defined in a competing setting. Maximum likelihood esimators are obtained using a modified Marquardt algorithm with strict convergence criteria based on the parameters and likelihood stability, and on the negativity of the second derivatives. The package also provides various post-fit functions including goodness-of-fit analyses, classification, plots, predicted trajectories, individual dynamic prediction of the event and predictive accuracy assessment. This paper constitutes a companion paper to the package by introducing each family of models, the estimation technique, some implementation details and giving examples through a dataset on cognitive aging

Testing for Welfare Comparisons when Populations Differ in Size

Assessments of social welfare do not usually take into account population sizes. This can lead to serious social evaluation flaws, particularly in contexts in which policies can affect demographic growth. We develop in this paper a little-known though ethically attractive approach to correcting the flaws of traditional welfare analysis, an approach that is population-size sensitive and that is based on critical-level generalized utilitarianism (CLGU). Traditional CLGU is extended by considering arbitrary orders of welfare dominance and ranges of “poverty lines” and values for the “critical level” of how much a life must be minimally worth to contribute to social welfare. Simulation experiments briefly explore the normative relationship between population sizes and critical levels. We apply the methods to household level data to rank Canada’s social welfare across 1976, 1986, 1996 and 2006 and to estimate normatively and statistically robust lower and upper bounds of critical levels over which these rankings can be made. The results show dominance of recent years over earlier ones, except when comparing 1986 and 1996. In general, therefore, we conclude that Canada’s social welfare has increased over the last 35 years in spite (or because) of a substantial increase in population size.CLGU, welfare dominance, FGT dominance, estimation of critical levels, welfare in Canada

Are there asymmetries in the effects of training on the conditional male wage distribution?

Recent studies have used quantile regression (QR) techniques to estimate the impact of education on the location, scale and shape of the conditional wage distribution. In our paper we investigate the degree to which work-related training – another important form of human capital – affects the location, scale and shape of the conditional wage distribution. Using the first six waves of the European Community Household Panel, we utilise both ordinary least squares and QR techniques to estimate associations between work-related training and wages for private sector men in ten European Union countries. Our results show that, for the majority of countries, there is a fairly uniform association between training and hourly wages across the conditional wage distribution. However, there are considerable differences across countries in mean associations between training and wages

How do Adolescents Spell Time Use?

We investigate how household disadvantage affects the time use of 15-18 year-olds using 2003- 2006 data from the American Time Use Survey. Applying competing-risk hazard models, we distinguish between the incidence and duration of activities and incorporate the daily time constraint. We find that teens living in disadvantaged households spend less time in nonclassroom schooling activities than other teens. Girls spend some of this time in work activities, suggesting they are taking on adult roles. However we find more evidence of substitution into unsupervised activities, suggesting that it may be less structured environments that reduce educational investment.Time use, adolescence, event history models

How Do Adolescents Spell Time Use?

We investigate how household disadvantage affects the time use of 15-18 year-olds using 2003-2006 data from the American Time Use Survey. Applying competing-risk hazard models, we distinguish between the incidence and duration of activities and incorporate the daily time constraint. We find that teens living in disadvantaged households spend less time in non-classroom schooling activities than other teens. Girls spend some of this time in work activities, suggesting they are taking on adult roles. However we find more evidence of substitution into unsupervised activities, suggesting that it may be less structured environments that reduce educational investment.event history models, adolescence, time use