Browsing by Author "Parsons, Charles K."

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    Application of a simplex process model to six years of cognitive development in four demographic groups
    (1979) Humphreys, Lloyd G.; Park, Randolph D.; Parsons, Charles K.
    A simplex process model of the cross-lagged correlation paradigm was applied to 16 tests administered to samples of black and white males and black and white females in Grades 5, 7, 9, and 11. Listening, a measure of aural comprehension, consistently anticipated individual differences on an intellectual composite in all four groups. The other achievement test of the STEP series anticipated individual differences on the so-called aptitude tests of SCAT, which in turn anticipated individual differences on the narrow information scores obtained from the Test of General Information (TGI). This model may be more powerful in revealing lags than the traditional methods of analyzing cross-lagged differences in longitudinal data. The model does not require stationarity and can produce a meaningful outcome in its absence.
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    Application of unidimensional item response theory models to mutidimensional data
    (1983) Drasgow, Fritz; Parsons, Charles K.
    A simulation model was developed for generating item responses from a multidimensional latent trait space The model permits the prepotency of a general latent trait underlying responses to all simulated items to be varied systematically. Five levels of prepotency were used to generate data sets The levels of prepotency ranged from a truly unidimensional latent trait space to a very weak general latent trait. Simulated item pools with guessing and without guessing were analyzed by the LOGIST computer program The general latent trait was recovered in data sets where the prepotency of the general latent trait was only moderate. Consequently, it appears that item response theory models can be applied to moderately heterogenous item pools under the conditions simulated here.
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    Search for a common factor model to describe a cross-lagged correlation difference
    (1978) Humphreys, Lloyd G.; Parsons, Charles K.
    This study describes the development of a common factor model for a cross-lagged difference involving a measure of aural comprehension and an intellectual composite. The direction of the difference was that the Listening Test predicted the composite more accurately than the composite predicted the Listening Test. A complex model which allowed seemingly identical common factors appearing at different ages to be highly, but imperfectly, correlated fit the 32 x 32 table of intercorrelations of 16 variables measured at each of two time periods. The model also described quite accurately the multiple correlations on which the cross-lagged difference was based. Aural comprehension at grade 5 was equidistant from the vectors of the two general factors at grades 5 and 11; but aural comprehension at grade 11, while close to the general factor at grade 11, was outside the space created by the two general factor vectors. Individual differences in aural comprehension anticipated by several years changes in rank on the general factor as defined by standard tests.