A study was made to ascertain how large a sample is needed to make media effectiveness decisions which are generalizable to the total educable mentally handicapped (EMH) population. The method employed in the study involved pretesting and posttesting a sample of 70 primary and intermediate EMH children on the content of a filmstrip. Statistical…

Incorporated in the media evaluation model developed by the Computer Based Project (Syracuse, N.Y.) is a procedure whereby independent samples are used to obtain baseline responses to cognitive question items. Items from two films are intermixed and presented after showing only one of the films; thus, the sample audience responds to questions from…