A simulation study was conducted to evaluate the
dependability of Stout’s T index of unidimensionality as
used in his DIMTEST procedure. DIMTEST was found to
dependably provide indications of unidimensionality, to
be reasonably robust, and to allow for a practical demarcation
between one and many dimensions. The procedure
was not affected by the method used to identify
the initial subset of unidimensional items. It was, however,
found to be sensitive to whether the multidimensional
data arose from a compensatory model or a
partially compensatory model. DIMTEST failed when the
matrix of tetrachoric correlations was non-Gramian and
hence is not appropriate in such cases. Index terms:
DIMTEST, essential unidimensionality, factor analysis,
item response models, Stout’s test of unidimensionality,
tetrachoric correlations, unidimensionality.
Hattie, John, Krakowski, Krzysztof, Rogers, H. Jane & Swaminathan, Hariharan. (1996). An assessment of Stout's index of essential unidimensionality. Applied Psychological Measurement, 20, 1-14. doi:10.1177/014662169602000101
Hattie, John; Krakowski, Krzysztof; Rogers, H. Jane; Swaminathan, Hariharan.
An assessment of Stout's index of essential unidimensionality.
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