Maximum likelihood estimation of Laplace parameters based on general type-II censored examples

In this paper, we derive the maximum likelihood estimators of the parameters of a Laplace distribution based on general Type-II censored samples. The resulting explicit MLE's turn out to be simple linear functions of the order statistics. We then examine the asymptotic variance of the estimates by calculating the elements of the Fisher information matrix.     

Reinforcement,stereotypy, and rule discovery

The effects of reinforced pretraining on subsequent rule discovery were examined with college students as subjects. Levels of behavioral stereotypy observed during reinforced and non-contingent pretraining were compared. During pretraining subjects received reinforcement if they pressed two keys in a particular sequence. During the problem session pressing each key four times was a necessary condition for reinforcement, but each problem had additional different requirements for reinforcement. Subjects were asked to solve the problems by discovering the rule that determined whether or not they received reinforcement. Levels of stereotyped responding during pretraining were equivalent for contingently and non-contingently trained subjects. During the problem session contingently pretrained, non-contingently pretrained, and naive subjects required equal numbers of trials to solve problems and solved the same number of problems. The results suggest that behavioral stereotypy observed in this experimental preparation may be due to repeated exposure to the task. Differences between the results observed in this study and that of Schwartz (1982) and implications for the use of reinforcement procedures in applied settings are discussed.

     

Higher order moments of order statistics from INID symmetric random variables

In this paper we present analogues of Balakrishnan's (1989) relations that relate the triple and quadruple moments of order statistics from independent and nonidentically distributed (I.NI.D.) random variables from a symmetric distribution to those of the folded distribution. We then apply these results, along with the corresponding recurrence relations for the exponential distribution derived recently by Childs (2003), to study the robustness of the Winsorized variance.     

Assessing clinical progress: A case study of Daryl

In this single case study, the authors conceptually framed their understanding of dissociation and splitting as defensive/adaptive coping mechanisms through which children respond to abusive/neglectful environments and the developmental deficits of abused/neglected children as related to failure in separation/individuation. Case study methodology with a nested experimental research design employed content analysis of process recordings to identify targeted defenses and developmental themes and then to assess therapeutic effectiveness during the first six months of psychodynamic play therapy with Daryl. In-session cliniial progress was assessed through charting changes in defenses and developmental themes, identifying degree of goal achievement, and clinically observing treatment stage progression. Visual analysis of the frequency charts identified a slight cyclical decline in use of splitting and guarding against dissociation and a somewhat uneven increase in the developmental theme of coexistence/integration. While these changes in targeted outcome variables were not statistically significant, the amount of change did exceed the predetermined outcome goals for decreased splitting and increased coexistence but not the goal of decreased guarding against dissociation. Review of the process recordings also identified clear markers of treatment progression through two therapeutic stages in the first six months of long term psychodynamic play therapy and further supported the clinical meaningfulness of the observed changes.     

A changed America? The effects of September 11th on depressive symptoms and alcohol consumption

In the weeks following the terrorist attacks of September 11, 2001, social commentators argued that America had profoundly "changed." In light of these arguments and the literature on disasters, we examine the immediate and longer-term mental health consequences of September 11th using a national sample of full-time American workers. We model the effects of temporal proximity to the attacks on depressive symptoms and alcohol consumption, while controlling for demographic characteristics. Our data revealed a significant increase in the number of depressive symptoms reported during the 4 weeks after the attacks. In the subsequent weeks, levels of depressive symptoms returned to pre-September 11th levels. Contrary to expectations, there was some indication of decreased alcohol consumption after September 11th, although these effects were modest. These analyses provide little support for popular assertions that September 11th resulted in lasting and measurable impacts on Americans' well-being.     

Do expressive mothers have expressive children? The role of socialization in children's affect expression

The effects of maternal expressiveness and children's gender on children's nonverbal expressiveness were assessed in two settings. In the laboratory, 30 boys and 30 girls of kindergarten age were unobtrusively videotaped while talking about happy, sad, and fearful experiences and while experiencing three social situations designed to elicit happy, disappointed, and apprehensive feelings. Videotapes were rated for emotion expression, using global ratings and EMFACS codes. In school, teachers rated these children's expression of four discrete emotions. In both the laboratory and school settings children were more positively expressive than negatively so, and positive and negative expressiveness were unrelated. In the laboratory children's positive expressiveness was consistent across the three social situations, but negative expressiveness varied across affective context. In both settings, children of low-expressive mothers were more positively expressive than children of high-expressive mothers, who tended to be more negatively expressive than children of low-expressive mothers. The difference in negative expression appeared most striking for anger. Gender was not predictive of children's expressiveness in either setting