| Summary: | The present study investigated potentially biased scale items on the Center for
Epidemiologic Studies Depression (CES-D) scale in a sample of 600 community-dwelling
adults between the ages of 17 and 87 years. The mean age was 46 years for males (N=310)
and 42 years for females (N=290). The 20-item CES-D was scored using two binary
methods (presence and persistence) and one ordinal method. Gender differential item
functioning (DIF) was explored using Zumbo's (1999) ordinal logistic regression method
with corresponding logistic regression effect size estimator with all three scoring methods.
After statistically matching males and females on the underlying ability, gender DIF was
found with the CES-D item crying for the ordinal and presence methods of scoring. The
persistence scoring method identified two DEF items (effort and hopeful), however, this
scoring method was of limited use due to low response rates on some items. Overall, the
results indicate that the scoring method has an effect on DEF; thus DEF is a property of the
item, scoring method, and purpose of the instrument.
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