Quantile based tests for exponentiality against DMRQ and NBUE alternatives

Quantile-based reliability analysis has received much attention recently. We propose new quantile-based tests for exponentiality against decreasing mean residual quantile function (DMRQ) and new better than used in expectation (NBUE) classes of alternatives. The exact null distribution of the test statistic is derived when the alternative class is DMRQ. The asymptotic properties of both the test statistics are studied. The performance of the proposed tests with other existing tests in the literature is evaluated through simulation study. Finally, we illustrate our test procedure using real data sets.     

A bivariate distribution with Lomax and geometric margins

We develop a stochastic model describing the joint distribution of $(X,N)$, where $N$ has a geometric distribution while $X$ is the sum of $N$ dependent, heavy-tail Pareto components. Models of this form arise in many applications, ranging from hydro-climatology to finance and insurance. We present fundamental properties of this vector, including marginal and conditional distributions, moments, representations, and parameter estimation. We also include an example from finance, illustrating modeling potential of this new bivariate distribution.     

Optimal consumption and portfolio selection with negative wealth constraints,subsistence consumption constraints,and CARA utility

We consider the optimal consumption and portfolio selection problem with constant absolute risk aversion (CARA) utility. The economic agent in this model receives constant labor income, and her economic behavior is restricted on consumption and wealth, which are called the subsistence consumption constraint and the negative wealth constraint. We use the convex duality method to derive the value function and the optimal policies in closed-form solutions. Also we illustrate some numerical examples.     

Mildly explosive autoregression with mixing innovations

In this paper, the limit distribution of the least squares estimator for mildly explosive autoregressive models with strong mixing innovations is established, which is shown to be Cauchy as in the iid case. The result is applied to identify the onset and the end of an explosive period of an econometric time series. Simulations and data analysis are also conducted to demonstrate the usefulness of the result.     

Restricted maximum likelihood estimation of joint mean‐covariance models

The class of joint mean‐covariance models uses the modified Cholesky decomposition of the within subject covariance matrix in order to arrive to an unconstrained, statistically meaningful reparameterisation. The new parameterisation of the covariance matrix has two sets of parameters that separately describe the variances and correlations. Thus, with the mean or regression parameters, these models have three sets of distinct parameters. In order to alleviate the problem of inefficient estimation and downward bias in the variance estimates, inherent in the maximum likelihood estimation procedure, the usual REML estimation procedure adjusts for the degrees of freedom lost due to the estimation of the mean parameters. Because of the parameterisation of the joint mean covariance models, it is possible to adapt the usual REML procedure in order to estimate the variance (correlation) parameters by taking into account the degrees of freedom lost by the estimation of both the mean and correlation (variance) parameters. To this end, here we propose adjustments to the estimation procedures based on the modified and adjusted profile likelihoods. The methods are illustrated by an application to a real data set and simulation studies. The Canadian Journal of Statistics 40: 225–242; 2012 © 2012 Statistical Society of Canada     

A generalized Fleming and Harrington's class of tests for interval‐censored data

The class $G^{\rho,\lambda }$ of weighted log‐rank tests proposed by Fleming & Harrington [Fleming & Harrington (1991) Counting Processes and Survival Analysis, Wiley, New York] has been widely used in survival analysis and is nowadays, unquestionably, the established method to compare, nonparametrically, k different survival functions based on right‐censored survival data. This paper extends the $G^{\rho,\lambda }$ class to interval‐censored data. First we introduce a new general class of rank based tests, then we show the analogy to the above proposal of Fleming & Harrington. The asymptotic behaviour of the proposed tests is derived using an observed Fisher information approach and a permutation approach. Aiming to make this family of tests interpretable and useful for practitioners, we explain how to interpret different choices of weights and we apply it to data from a cohort of intravenous drug users at risk for HIV infection. The Canadian Journal of Statistics 40: 501–516; 2012 © 2012 Statistical Society of Canada     

Gender-specific differences in labor market adjustment patterns: Evidence from the United States

Do men and women behave differently while adjusting labor supply over the business cycle? Using data from the United States, we show that women are significantly more likely to adjust along the intensive margin (number of hours), while men adjust more along the extensive margin (employment). Older, single, and divorced/widowed adjust predominantly along the extensive margin.     

Understanding innovation performance and its antecedents: A socio-cognitive model

Little attention in the previous literature has been paid to understanding employees’ factors that drive customer development knowledge and performance from the perspective of social psychology. Drawing on social cognitive theory, this study validates a research model that examines the above issue. In the setting of new product development across high-tech firms in Taiwan, this study postulates that innovation self-efficacy, role conflict, and role ambiguity influence innovation performance directly and indirectly via the mediation of customer knowledge development and innovation outcome expectation. This study contributes to the social science literature by applying social cognitive theory to the rarely explored area of innovation performance and by presenting an operationalization of role stressors (i.e., role ambiguity and role conflict) in the area. Lastly, managerial implications and limitations from the empirical findings are provided.     

Measuring inequality with asset indicators

This paper examines whether, in the absence of information on household income or consumption, data on household infrastructure, building materials, and ownership of certain durable assets can be used to measure inequality in living standards. Principal components analysis is used to obtain a relative measure of inequality, and a bootstrap prediction method is provided for use when auxiliary surveys are available. Mexican data is used to show that the inequality methods provided do provide reasonable proxies for inequalities in living standards. An application finds that after controlling for household income and demographics, school attendance of boys in Mexico is negatively related to state-level inequality.     

Altruism and the macroeconomic effects of demographic changes

In this paper we show that the macroeconomic effects of demographic changes strongly depend on the degree of altruism and on the specification of the intertemporal utility function. We allow for agents either to be altruistic in the sense of Barro (1974) or non-altruistic. In the latter case, generations are heterogeneous like in the „unloved children” model of Weil (1989). In the former case, where the model is a standard Ramsey model with identical agents, we distinguish a Millian and a Benthamite intertemporal utility function. For each of these models, we study the effects of an anticipated and unanticipated permanent decline in population growth as well as the consequences of a baby-boom/baby-bust scenario. Received April 17, 1996/Accepted December 10, 1996