Current Directions in Mediation Analysis

ABSTRACT— Mediating variables continue to play an important role in psychological theory and research. A mediating variable transmits the effect of an antecedent variable on to a dependent variable, thereby providing more detailed understanding of relations among variables. Methods to assess mediation have been an active area of research for the last two decades. This paper describes the current state of methods to investigate mediating variables.     

Same-sex and cross-sex siblings: Activity choices,roles, behavior,and gender stereotypes

Forty same-sex and cross-sex school-aged sibling pairs were observed in their homes during self-selected activities. The sex role learning index (SERLI) and a sex-typing room analysis were administered for the younger siblings, and maternal questionnaire information was obtained. Sibling gender constellation was associated with reliable differences in activity choices during the unstructured observations. Male dyads interacted less than other sibling groups, while older sisters in female dyads engaged in the most teaching. Older female siblings, regardless of the gender of the younger sibling, assumed the manager role frequently. Dyads containing an older girl also exhibited the greatest role asymmetrics. Affective differences related to gender constellation were also noted. Younger girls with older brothers and younger boys with older sisters evidenced the least gender stereotyping.     

An Assessment of the Utility of Suicide Prediction*

ABSTRACT: Efforts to predict a future event assume varying levels of confidence depending on its base rate and the error rate of the prediction instrument. Most researchers working with suicide prediction instruments seem tacitly to assume they will be able to predict a future suicide most of the time. Applying basic decision theory on a neuropsychiatric hospital population indicates that researchers using a prediction schedule will be unlikely to predict a future suicide beyond a 20% level of efficiency. Contrary to the general clinical view, eliminating false negatives was shown to be more practical than eliminating false positives in increasing the efficiency of a predictive schedule.     

Distribution of the product confidence limits for the indirect effect: Program PRODCLIN

This article describes a program, PRODCLIN (distribution of the PRODuct Confidence Limits for INdirect effects), written for SAS, SPSS, and R, that computes confidence limits for the product of two normal random variables. The program is important because it can be used to obtain more accurate confidence limits for the indirect effect, as demonstrated in several recent articles (MacKinnon, Lockwood, & Williams, 2004; Pituch, Whittaker, & Stapleton, 2005). Tests of the significance of and confidence limits for indirect effects based on the distribution of the product method have more accurate Type I error rates and more power than other, more commonly used tests. Values for the two paths involved in the indirect effect and their standard errors are entered in the PRODCLIN program, and distribution of the product confidence limits are computed. Several examples are used to illustrate the PRODCLIN program. The PRODCLIN programs in rich text format may be downloaded from www.psychonomic.org/archive.     

Statistical properties of four effect-size measures for mediation models

This project examined the performance of classical and Bayesian estimators of four effect size measures for the indirect effect in a single-mediator model and a two-mediator model. Compared to the proportion and ratio mediation effect sizes, standardized mediation effect-size measures were relatively unbiased and efficient in the single-mediator model and the two-mediator model. Percentile and bias-corrected bootstrap interval estimates of ab/s _Y , and ab(s _X )/s _Y in the single-mediator model outperformed interval estimates of the proportion and ratio effect sizes in terms of power, Type I error rate, coverage, imbalance, and interval width. For the two-mediator model, standardized effect-size measures were superior to the proportion and ratio effect-size measures. Furthermore, it was found that Bayesian point and interval summaries of posterior distributions of standardized effect-size measures reduced excessive relative bias for certain parameter combinations. The standardized effect-size measures are the best effect-size measures for quantifying mediated effects.     

兒童第一和第二信号系統的相互动力傳遞的实驗研究

<正> 巴甫洛夫关于两种信号系統的学說指出,我們关于周围环境的感觉和表象乃是現实的第一信号系統,而詞则构成現实的第二信号系統;第二信号系統是在第一信号系統的基础上形成起来的,它們二者是密切联系着、相互作用着的。由于巴甫洛夫的这一偉大学說的啟示,在高級神經活动生理学和心理学这两个領域里已展开了和展开着一系列关于两种信号系統相互作用的实驗研究。     

Children: Yes or No,A Decision-Making Program for Women

This article describes how a workshop for career women who were experiencing difficulty in deciding whether or not to have a child was designed, conducted, and evaluated.