No abstract

We compared the accuracy of momentary time sampling (MTS) and partial interval recording (PIR) in estimating both absolute behavioral levels and relative change. A computer randomly generated runs of pseudobehavior varying in duration and rate and simulated MTS and PIR of each run. Results indicated that when estimating absolute behavioral levels, duration rather than rate should be used as the dependent measure, and MTS is more accurate than PIR. In contrast, PIR is the more sensitive method for detecting relative changes in behavioral levels, although, at high rates, PIR tends to underestimate the degree of change. An examination of these studies indicates, however, that neither adequately equated the conditions under which MTS and PIR were compared, and neither explored the possible independent influence of behavioral parameters (e.g., duration of behavioral episodes and rate of responding) on the accuracy of the techniques. Furthermore, the analyses applied to the data were, in both cases, limited to a comparison of accuracy in estimating absolute behavioral levels. Although such estimation is, in many situations, important (e.g., in determining whether an intervention is necessary), an equally important consideration, particularly in intervention research, is accuracy in the estimation of relative changes in behavioral level.In view of the limitations in the studies by Repp et al. (1976) and Powell et al. (1977), we decided to examine furiher the accuracy of comparable MTS and PIR procedures in estimating both absolute behavioral levels and relative changes, for various durations and rates of behavior. We hope that our results may help to provide researchers and practitioners with dearer guidelines on the relative merits of the two techniques and on the conditions in which one method may be preferred.

Ten teachers in infant schools, 10 in junior schools and 10 in secondary schools had their teaching recorded. Subsequent analysis was made of the teachers' use of questions categorised as of fact, closed solution, open solution, task supervision and routine. When the first two categories were combined, the results for the junior schools were very similar to those reported by his colleagues in 1980 and1999. Moreover, the results for both the infant and secondary schools differed very little from those of the junior schools. Some implications of these results are discussed.

That the results for approval and disapproval rates agree with those of the 1980s in which differing methodologies were used in different school systems is encouraging evidence that teachers are using appropriate verbal responses to their pupils. Some of the more detailed results of the investigation do, however, indicate areas for concern.

The inherent properties of momentary time sampling (MTS) and partial interval recording (PIR) are examined. Findings derived from computer simulation investigations are discussed in terms of the mode of operation of the two time-sampling techniques. It is seen that the advantage of MTS is that it can, under certain restricted circumstances, estimate absolute duration of behaviour occurring. The important disadvantage of MTS is that it is relatively insensitive when estimating degree of change of behaviour. In contrast, although PIR cannot accurately measure absolute duration it is more sensitive to behaviour change than is MTS. It is concluded that the practitioner who wishes to use one of these methods of time sampling must carefully consider the aims and possible effects of the investigation before deciding which method to use.In the last two decades the behavioural approach has developed rapidly in this country. A variety of applications has been seen in numerous articles and widespread usage is evident in the various British texts now available to practitioners (Westmacott and Cameron, 1981;Harrop, 1983; Wheldall and Merrett, 1984;Cheesman and Watts, 1985). A worrying aspect of this development is, however, an apparent neglect of methodological issues. Whilst attention was drawn to a number of the issues some nine years ago (Harrop, 1980), and indeed repeatedly elsewhere for the past two decades, there has been little indication in subsequent publications that any account has been taken by practitioners. Furthermore, in recent times, there have been a number of methodological investigations, particularly in the area of measurement, the results of which do not seem to have been incorporated into behavioural research.It seems likely that the reasons for this neglect of methodological findings lie in the practitioner's eagerness to engage in treatment coupled with the inaccessibility and sheer complexity of some of the methodological work. Nevertheless, if behavioural work is to progress fruitfully, practitioners must