A number of potential threats to internal validity in true experiments are discussed. Programmatic research efforts proceeding from established correlational findings to experiments employing random assignment are described and used as referents in discussions of validity considerations. The collection of observational data is recommended for use…

The purpose of this study was to measure the effectiveness of a monolingual versus a bilingual approach to the education of second-grade, Spanish-speaking children in New York City. The results were determined by measuring achievement in reading, which showed that the bilingual approach was indeed the more effective. The report includes an…

Problems with conducting randomized field experiments in education are explored. Focus is on problems encountered while evaluating a group of dropout prevention projects. Project planners were asked to manipulate the subject eligibility criteria until they identified as eligible three to four times as many students as they could serve. They were…