Thin slice sampling of video footage for mother/child interaction: application to single cases

Objective: The purpose was to test the reliability of short samples of parent/child interaction for use in single-subject research. Methods: Four variable pairs of mother/child behaviour were coded for seven mother/child play sessions. Each session lasted 20 minutes and 18 minutes of the session was behaviourally coded using frame-by-frame analysis. The co-occurrence of the mother/child behaviours within a given time window was computed and an odds ratio was calculated for the co-occurrence of the targeted behaviours. The play session was divided into shorter segments (three, six and nine minutes) and odds ratios of the variable pairs from the shorter segments were compared to the odds ratios from the entire session. Results: Segments of three and six minutes did not yield the same pattern of results as the entire session. Conclusions: In single-subject research, evidence of the reliability of the time segment for behavioural coding should be reported in the methods section of original research manuscripts.