Accuracy of observational data with whole interval, partial interval, and momentary time-sampling recording techniques

The purpose of the study was to compare the accuracies obtained from whole interval, partial interval, and momentary time-sample recording procedures. Two types of accuracies were defined. Between-methods accuracy is the degree to which an observer using a particular recording method agrees with a standard using a continuous recording method. Within-methods accuracy is the degree to which an observer and a standard agree when both use the same recording method. Fifty-four undergraduate students viewed a videotape of a woman twisting her hair and recorded the occurrence or nonoccurrence of the behavior using one of the three recording methods. Tapes were divided into segments with low, intermediate, and high rates of behavior. Partial and whole interval recording obtained poorer between-methods accuracies than momentary time sampling. Results showed that whole interval and momentary time-sampling procedures yielded higher within-method accuracies than partial interval recording. Thus, momentary time-sampling recording provided the advantages of both greater representativeness and as few or fewer observer errors than whole or partial interval recording procedures. Use of the interval recording methods by researchers must be justifiable within this framework.