• functional analysis;
  • self-injurious behavior;
  • aggression

We compared results obtained from 50 sets of functional analysis data from assessments of self-injurious behavior (SIB), 35 of which showed clear response patterns and 15 of which were undifferentiated, with those obtained from two abbreviated methods of assessment: (a) a brief functional analysis, consisting of the first session of each condition from the full functional analysis, and (b) a within-session analysis, in which data from the brief analysis were regraphed to show minute-by-minute changes in response rates during a session. Results indicated that outcomes of the brief and within-session analyses corresponded with those of the full functional analyses in 66.0% and 68.0% of the cases, respectively. Further examination of results indicated a tendency for the brief analysis to identify a large proportion of positive cases (both true and false positives) and for the within-session analysis to identify a large proportion of negative cases (true and false negatives).