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Browsing by Author "Bell, Richard C."

Now showing 1 - 3 of 3
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    Common space analysis of several versions of the Wechsler Intelligence Scale for Children
    (1981) Bell, Richard C.
    A joint analysis was made of three versions of the Wechsler Intelligence Scale for Children using an individual differences multidimensional scaling approach. The versions of the test considered were the original version, an Australian partial revision, and the current revised version. Common Space Analysis of the correlation data from the manuals showed a common three-dimensional structure. There was a compact group of verbal subtests and a more loosely defined group of performance tests. Arithmetic, Digit Span, and Coding were found to be more peripheral to the battery. No systematic variations in structure could be related to the different age groups.
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    Conditional independence in a clustered item test
    (1988) Bell, Richard C.; Pattison, Philippa E.; Withers, Graeme P.
    Although the assumption of local independence underlies all latent trait theories in mental testing, it has rarely been empirically examined. In this study of a clustered item test (the Australian Scholastic Aptitude Test), a loglinear modeling approach was used to examine the conditional independence of items both within and between clusters. In general, although relationships between items were usually positive (as required for theories involving monotone item trace lines), conditional independence was not found. Departures from independence were more marked in items within clusters rather than between clusters, and also among items based on mathematical rather than verbal material. Another finding was the tendency for departures from independence to increase with ability (as measured by the score on other items).
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    Test length and validity
    (1980) Bell, Richard C.; Lumsden, James
    The effect of test length on predictive validity is examined empirically by successively omitting the poorest items and by calculating the correlations between the reduced test scores and the criterion. It was found, for four tests, that the curve of validity against test length had a very gentle slope for the longer tests and that all tests could be reduced by more than 60% without appreciable decreases in validity.