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Assessing Invariance of Factor Structures and Polytomous Item Response Model Parameter Estimates

The purpose of the present study was to examine the
invariance of the factor structure and item response model
parameter estimates obtained from a set of 27 items
selected from the 2002 and 2003 forms of Your First College
Year (YFCY). The first major research question of the
present study was: How similar/invariant are the factor
structures obtained from two datasets (i.e., identical
items, different people)? The first research question was
addressed in two parts: (1) Exploring factor structures
using the YFCY02 dataset; and (2) Assessing factorial
invariance using the YFCY02 and YFCY03 datasets.
After using exploratory and confirmatory and factor
analysis for ordered data, a four-factor model using 20
items was selected based on acceptable model fit for the YFCY02 and YFCY03 datasets. The four factors (constructs)
obtained from the final model were: Overall Satisfaction,
Social Agency, Social Self Concept, and Academic Skills.
To assess factorial invariance, partial and full factorial
invariance were examined. The four-factor model fit both
datasets equally well, meeting the criteria for partial and
full measurement invariance.
The second major research question of the present
study was: How similar/invariant are person and item
parameter estimates obtained from two different datasets
(i.e., identical items, different people) for the
homogenous graded response model (Samejima, 1969) and the
partial credit model (Masters, 1982)?
To evaluate measurement invariance using IRT methods,
the item discrimination and item difficulty parameters
obtained from the GRM need to be equivalent across
datasets. The YFCY02 and YFCY03 GRM item discrimination
parameters (slope) correlation was 0.828. The YFCY02 and
YFCY03 GRM item difficulty parameters (location)
correlation was 0.716. The correlations and scatter plots
indicated that the item discrimination parameter estimates
were more invariant than the item difficulty parameter
estimates across the YFCY02 and YFCY03 datasets.

Identiferoai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-12-8673
Date2010 December 1900
CreatorsReyes, Jennifer McGee
ContributorsThompson, Bruce
Source SetsTexas A and M University
Languageen_US
Detected LanguageEnglish
Typethesis, text
Formatapplication/pdf

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