Donald Ary

A post hoc correction procedure for systematic errors in time-sampling duration estimates

Numerous previous studies have shown that partial-interval sampling in direct observation systematically overestimates duration and underestimates frequency. Whole-interval sampling systematically underestimates both duration and frequency. This paper presents a post hoc method through which the systematic errors in duration estimates in partial-interval sampling and whole-interval sampling can be minimized.

The use of momentary time sampling to assess both frequency and duration of behavior

When the time-sampling interval size can be set so it is smaller than both the shortest behavior instance and the shortest interresponse time, momentary time sampling will yield an accurate count of the frequency of behavior occurrence. It will also yield an unbiased estimate of behavior duration.

Variables influencing one-zero and instantaneous time sampling outcomes

Previous studies have shown that instantaneous time sampling results are more highly correlated with true duration than are one-zero sampling results. One-zero results, however, reflected a composite of both duration and frequency better than did instantaneous results. It is shown in this analysis that these outcomes are the logical result of the definitions of the two sampling modes. When interval lengths meet specific requirements, correct frequency counts can be obtained with either mode and systematic duration error with one-zero sampling can be eliminated by subtracting frequency from the number of intervals scored ‘one.’

Institutional Productivity Ratings Based on Publications in Reading Journals: 1978-1983.

Abstract The productivity of institutions was assessed by counting articles published in eight reading journals from 1978–1983. The top twenty‐five were all state assisted institutions. Twelve of these were among the top twenty‐five in an earlier study by Hopkins (1979). Other rankings were compiled by: 1) calculating productivity in two high prestige research journals and 2) calculating articles per faculty member in the same institutions.

Scholarly productivity in mental retardation

The most productive institutions in social, educational, and psychological research in mental retardation were identified by noting the affiliations of authors who have published recently in the field. A frequency count was made of the studies published, giving credit to universities on the basis of the percentage of the total contribution provided by particular investigators, up to a maximum of one full publication. Also, the number of publications represented by each particular university was computed. The implications of these particular data are briefly discussed.

A decision tree approach to selecting an appropriate observation reliability index

Based on the conceptual framework outlined by Cone (1986) and Suen (1988), a practical decision tree is developed as an aid for the selection of observational reliability indices.

Graphic comparisons of interobserver agreement indices

How changes in the interobserver agreement and disagreement cells in the reliability matrix are reflected differently in eight commonly used reliability indices is shown graphically. Indices which take into account expected chance difference are compared to those indices which do not. Differences between indices which do and do not treat the agreement and the disagreement cells equally are also illustrated.