Recording units: Events versus intervals

The title of this chapter, Recording behavioral sequences, suggests two different but somewhat related topics. The chapter could deal primarily with mechanical matters and describe devices used to record data, or it could deal just with conceptual matters and describe different strategies for collecting data about behavior sequences. Actually, this chapter will be a mixture of both, although conceptual and strategic matters will be stressed.

One important issue has already been raised by the example of the Bakeman and Brownlee (1980) study of parallel play in chapter 1, and that is the issue of “units.” Before selecting a particular recording strategy, an investigator needs first to decide what “units” are to be used for recording.

As we use the term, the recording unit indentifies what prompts the observer to record, and usually is either an interval or an event. For example, an investigator might choose to code time intervals, as Bakeman and Brownlee did, assigning codes to successive time intervals. This is a common strategy, but for many purposes more accurate data result when the events themselves are coded instead. In such cases, observers wait for an event of interest to occur. When one occurs, they code it (i.e., note what kind of event it was) and perhaps record onset and offset times for the event as well.

Which is better, to code events or to code intervals? That depends on a number of factors, including the kind and complexity of the coding scheme, the desired accuracy for the data, and the kind of recording equipment available.