Estimation with right‐censored observations under a semi‐Markov model

The semi‐Markov process often provides a better framework than the classical Markov process for the analysis of events with multiple states. The purpose of this paper is twofold. First, we show that in the presence of right censoring, when the right end‐point of the support of the censoring time is strictly less than the right end‐point of the support of the semi‐Markov kernel, the transition probability of the semi‐Markov process is nonidentifiable, and the estimators proposed in the literature are inconsistent in general. We derive the set of all attainable values for the transition probability based on the censored data, and we propose a nonparametric inference procedure for the transition probability using this set. Second, the conventional approach to constructing confidence bands is not applicable for the semi‐Markov kernel and the sojourn time distribution. We propose new perturbation resampling methods to construct these confidence bands. Different weights and transformations are explored in the construction. We use simulation to examine our proposals and illustrate them with hospitalization data from a recent cancer survivor study. The Canadian Journal of Statistics 41: 237–256; 2013 © 2013 Statistical Society of Canada     

Assessing student learning in the context of evaluating a chance course

This paper describes the use of different assessment methods to evaluate Chance courses in the NSF-funded Chance project. Multiple methods were used to measure changes in students' attitudes and beliefs about statistics, reasoning about probability and statistics, and ability to critique a newspaper article that reports statistical results. Samples of assessment materials and scoring rubrics used in the evaluation are included.     

The therapeutic value of women's adult friendships

Abstract

In 1980, thirty‐five years after the end of World War II, the long‐term impact of war‐trauma on individuals’ lives led to concern about Post‐Traumatic Stress Disorder. While the focus here is not on “disorders,” it is on interactive patterns of “defensive” caretaking behaviors which contribute to intergenerational transmission of anxiety, silence and losses related to the Holocaust. In this long‐term group, defensive caretaking patterns are conceptualized as second‐generation behaviors which focus on parental needs thereby avoiding addressing second‐generation vulnerabilities. Relevant concepts of Sullivan, Winnicott, Bion and Fairbairn are applied. In an innovative trauma group design, defensive caretaking patterns are illustrated through clinical examples and interventions by the therapist as a “validating object” work to mitigate transmission to still the next generation.     

Auswirkungen von Downsizing-Maßnahmen auf das organisationale Commitment der verbleibenden Mitarbeiter: Ein Vorher-Nachher-Vergleich

This study examines the consequences of downsizing efforts on organizational commitment, job satisfaction and work motivation of the remaining workforce (?survivors“) in a middle-sized telecommunication company. Employees were surveyed five months prior to the downsizing process (n=150) and eleven months thereafter (n=160). The assessment of organizational commitment was based on a questionnaire that was developed by Allen and Meyer (1990) within the scope of their three-components-model which includes affective, continuous and normative commitment. Although layoffs — as one part of the whole downsizing process — were not implemented in the investigated company, but only in a sister enterprise, which is part of the same holding, the affective commitment of employees towards their corporation dropped. On the other hand, the normative and the balanced commitment remained constant. Moreover, every second survivor showed reduced job satisfaction and work motivation. It should be noted that although the results of reorganisation and restructuring did not directly affect the employees of the investigated company, the emotional linkage between employees and employer was affected in a negative way. Additional findings from qualitative interviews suggest that restructuring was perceived to cause a crack in the prevailing corporate culture and the psychological contract. In addition, a deterioration of work conditions through work overload resulted.     

Pseudolikelihood estimation in a class of problems with response-related missing covariates

Many practical situations involve a response variable Y and covariates X , where data on (Y, X ) are incomplete for some portion of a sample of individuals. We consider two general types of pseudolikelihood estimation for problems in which missingness may be response-related. These are typically simpler to implement than ordinary maximum likelihood, which in this context is semiparametric. Asymptotics for the pseudolikelihood methods are presented, and simulations conducted to investigate the methods for an important class of problems involving lifetime data. Our results indicate that for these problems the two methods are effective and comparable with respect to efficiency.     

The Impact of Educational Homogamy on Isolated Illiteracy Levels

In this article, we explore the impacts that education expansion and increased levels in educational homogamy have had on couples’ isolated illiteracy rates, defined as the proportion of illiterates in union that are married to an illiterate partner. First, we develop the methodology to decompose isolated illiteracy rates into two main components: one related to level of homogamy among illiterates, and the other related to the educational distribution of the spouses. Second, we use harmonized international census microdata from IPUMS and DHS data for 73 countries and 217 samples to investigate which of the two components is more important in shaping the level of isolated illiteracy. Our results indicate that the expansion of literacy has been more powerful than the increases in the tendency toward homogamy in its impact on isolated illiteracy rates. As the percentage of illiterates decreases over time, an increasingly large proportion of them marry literate individuals, showing that opportunities for intermarriage among illiterates expand despite the strengthening of homogamy.