The purpose of this article is to summarize the current literature on the accuracy and reliability of interval systems using data from previously published experimental studies that used human observations of behavior or computer simulations. The authors reported that, based on the review of previous comparisons, none of the interval systems were accurate estimates of frequency; thus, event recording should be used to measure counts of behavior in early childhood settings, and momentary time sampling (MTS) may be appropriate and feasible for estimating duration, but only if random error is considered, and that partial (PIR) and whole interval recording (WIR) systems are inappropriate unless a statistical correction procedure is devised.
Lane, Justin D. & Ledford, Jennifer R. (2014). Using Interval-Based Systems to Measure Behavior in Early Childhood Special Education and Early Intervention. Topics in early childhood special education, 34, 83-93.