Used structural equation modeling for comparative treatment outcome research conducted with heterogeneous clinical subpopulations within large multimodality treatment settings. Evaluated effect of early period of treatment on daily lives of 486 clients in 2 drug abuse treatment modalities (methadone maintenance and outpatient counseling).…

The validity of true experiments is threatened by a class of self-report biases that affect all respondents at pretest, but which are diminished by treatment. Four of these inaccurate self-evaluation biases are discussed. Means of detection include external criteria, special conditions of measurement, and retrospective pretests. (TJH)