Koh, William Siaw Yen and Ong , Saw Lan
(2012)
Validating Student-Parent Actions Model (Spa) Of
Consistency Using The Rasch Measurement Model.
The Asia Pacific Journal of Educators and Education (formerly known as Journal of Educators and Education), 27 (1).
pp. 1-20.
ISSN 2289-9057
Abstract
The objective of this paper is to investigate the consistency of item selection
and the existence of unidimensionality within each construct of the Student-Parent
Actions Model (SPA) measurement scale using item response theory (Rasch
measurement model). Based on Rasch model, which uses the WINSTEPS program, 373
students' responses were analysed. The sample group, which had a mean age of 16.41
years, was selected from five secondary schools through convenience sampling. The
initial 62 items of SPA were analysed within the eight 'a priori' hypothesised dimensions.
Rasch's misfit statistics were used to eliminate items that violated the infit and outfit
MNSQ criteria of being between 0.70 and 1.30. In combination with the first principal
component analysis of standardised residual (PCAR), Rasch's fit statistics were used to
analyse unidimensionality within each individual construct. From the Rasch analysis
results, 35 items were selected. In total, 27 items were similar to the SPA selected
through structural equation modelling (SEM) analysis. All eight constructs exhibited
unidimensionality, as PCAR analysis showed explained variances ranging from 47.10%
to 73.6% for each individual construct. However, the eigenvalues of unexplained
variances in the first contrast were all less than 3.0 indicating unidimensionality within
each construct. Overall, SPA exhibited high consistency in the selection of items between
the Rasch and SEM methods. When compared to the original SPA, the high percentage of
similarity (approximately 80%) for the selected items indicated item selection stability for
SPA across the two methods. Multidimensionality for the instrument was also detected.
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