Attrition in prevention research

Abstract

Selective attrition can detract from the internal and external validity of longitudinal research. Four tests of selective attrition applicable to longitudinal prevention research were conducted on data bases from two recent studies. These tests assessed (1) differences between dropouts and stayers in terms of pretest indices of primary outcome variables (substance use), (2) differences in change scores for dropouts and stayers, (3) differences in rates of attrition among experimental conditions, and (4) differences in pretest indices for dropouts among conditions. Results of these analyses indicate that cigarette smokers, alcohol drinkers, and marijuana users are more likely to drop out than nonusers, limiting the external validity of both studies. For one project, differential rates of attrition among conditions suggested a possible attrition artifact which will interfere with interpretation of outcome results, possibly masking true program effectiveness. Recommendations for standardizing reports of attrition and for avoiding attrition through second efforts are made.

The Työhön Job Search Program in Finland: Benefits for the unemployed with risk of depression or discouragement.

“…The attrition in experimental design was analyzed following the recommendations of Hansen, Collins, Malotte, Jonson, and Fielding (1985). The dropout effects in T2 and T3 were controlled, as well as the no-show bias in the intervention.…”

Developmental trajectories of self-management skills and adolescent substance use / Desarrollo de habilidades de autocuidado y uso de sustancias en adolescentes

“…From the 7th to 8th grade there was a loss of 17.7% of the students and an additional 7.4% and 6.7%, respectively, were lost in the two subsequent follow-up assessments (final panel sample N=2,277). The rate of attrition is moderate but does not exceed acceptable standards for conducting school-based drug abuse prevention studies (e.g., Hansen, Collins, Malotte, Johnson, & Fielding, 1985). Attrition analyses were conducted to determine whether any systematic bias was associated with the resultant panel sample.…”

Seven Ways To Increase Power Without Increasing N

“…In some studies where the treatment is aversive in some way, treatment group subjects drop out at a higher rate; in other studies where the treatment is a plum and nothing is done to compensate the control group, the opposite occurs. In substance use prevention studies, high-risk subjects are more likely to drop out (Hansen et al 1985). Attrition can even reflect a political problem as, for example, when an institution like a school or a school district drops out of a study ).…”