Effects of setting and number of observations on generalizability of parent-child interactions in childhood obesity treatment

The generalizability of behaviors across observational conditions is a critical issue in behavioral assessment. Generalizability theory was used to examine two aspects of audio recorded parent-child interactions recorded over 6 days of home measurement and 1 day of laboratory measurement in a behavioral treatment program for childhood obesity. Families audiotaped parent-child home meetings during which they reviewed self-monitored diet and exercise records that were coded for the following types of interactions: praise statements, negative statements, prompts for new behaviors, and statements promoting problem solving. A similar meeting was audiotaped in our laboratory. The first question explored was the number of measurements needed to generalize to the universe of the six home measures. Results showed an increase in generalizability over measurements for each behavioral category. Using generalizability coefficients of .60 or more, praise, negative comments and prompts, respectively, could be reliably observed based on 1, 4, or 4 days of measurement. Second, the effects of setting (laboratory versus home) were assessed for 1 day of measurement in each environment. Again using generalizability coefficients of .60, generalizability analysis showed that the lab setting could not be generalized to the home setting based on 1 day of measurement, with generalizability coefficients ranging from .27 for negative comments to .57 for praise. Results suggest that 4 days of behavioral assessment in the home can be used to establish generalizable data for all the dependent measures studied. However, generalizability coefficients suggested that 1 day of laboratory measurement was not adequate to generalize to typical home behavior.