Effects of session duration on functional analysis outcomes.

We examined the extent to which variations in session duration affected the outcomes of functional analyses. Forty-six individuals, all diagnosed with mental retardation and referred for assessment and treatment of self-injurious or aggressive behavior, participated in functional analyses, consisting of repeated exposure to multiple test conditions during 15-min sessions. For each set of assessment data, new data sets based on session durations of 10 and 5 min were prepared by deleting data from the last 5 and 10 min, respectively, of each session. Each graph (N = 138) was then reviewed individually by graduate students who had previous experience conducting and interpreting functional analyses, but who were blind to both participant identity and session duration. Interpretations of behavioral function based on the 10- and 5-min data sets were then compared with those based on the 15-min data sets. All of the 10-min data sets yielded interpretations identical to those based on 15-min data sets. Interpretations based on the 5-min and 15-min data sets yielded three discrepancies, all of which were the result of increased response rates toward the latter parts of sessions. These results suggest that the efficiency of assessment might be improved with little or no loss in clarity by simply reducing the duration of assessment sessions.