Abstract
The measurement error of time-sampling observation systems, used to estimate the frequencyof behavioral events, was analyzed by means of a five-factor design, computer simulation experiment. The first three factors represented response parameters: the relative frequency and duration of the behavior and the pattern of response distribution. For each combination of frequency, pattern, and duration, five simulated behavior events were generated within a simulated observation period of 900 sec. A total of 21 different time-sampling systems was employed. As a fourth factor three different observe and record lengths were included (6, 12, and 60 sec). In addition, there were seven different ratios of “observe” to “record” interval length (5∶1, 3∶1, 2∶1, 1∶1, 1∶2, 1∶3, and 1∶5) representing the fifth factor. Thus, 21 time-sampling systems scanned a total of 120 different behavior simulations from 24 types of behavior parameter combinations. The data were analyzed by means of a five-factor (2 × 3 × 4 × 3 × 7) analysis of variance with repeated measures on two factors. The study demonstrated that time sampling leads to high average measurement errors, which are determined by complex interrelationships among a variety of variables. Choosing a time-sampling system arbitrarily may lead to highly erroneous data. It was also shown, however, that time-sampling systems have the potential to yield very accurate results. An empirical selection procedure for time-sampling intervals is proposed to minimize measurement error. Exemplary tables are presented from which time-sampling parameters can be chosen given that the rate, duration, and pattern of occurrence of a behavior to be observed are known.
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The authors thank I. Florin, H. H. Schulze, and G. Sommer for critical readings of early drafts of the manuscript and Marsha Stephens for assistance in developing programs for the computer simulations.
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Rojahn, J., Kanoy, R.C. Toward an empirically based parameter selection for time-sampling observation systems. J Psychopathol Behav Assess 7, 99–120 (1985). https://doi.org/10.1007/BF00961077
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DOI: https://doi.org/10.1007/BF00961077