Effect sizes for experimenting psychologists.

This article describes three families of effect size estimators and their use in situations of general and specific interest to experimenting psychologists. The situations discussed include both between- and within-group (repeated measures) designs. Also described is the counternull statistic, which is useful in preventing common errors of interpretation in null hypothesis significance testing. The emphasis is on correlation (r-type) effect size indicators, but a wide variety of difference-type and ratio-type effect size estimators are also described.     

Injury control. What psychologists can contribute.

Psychologists are inadequately represented in the injury control field, despite the size of the problem and the importance of behavioral factors in injury. Using motor vehicle injuries as an example, this article discusses modern injury control principles and the role psychologists can play in injury reduction.