Reliability and validity of 4-point and 6-point
scales were assessed using a new model-based approach
to fit empirical data. Different measurement
models were fit by confirmatory factor analyses of a
multitrait-multimethod covariance matrix. 165 graduate
students responded to nine items measuring three
quantitative attitudes. Separation of method from trait
variance led to greater reduction of reliability and
heterotrait-monomethod coefficients for the 6-point
scale than for the 4-point scale. Criterion-related validity
was not affected by the number of scale points. The
issue of selecting 4- versus 6-point scales may not be
generally resolvable, but may rather depend on the
empirical setting. Response conditions theorized to influence
the use of scale options are discussed to provide
directions for further research. Index terms:
Likert-type scales, multitrait-multimethod matrix, reliability,
scale options, validity.
Chang, Lei. (1994). A psychometric evaluation of 4-point and 6-point Likert-type scales in relation to reliability and validity. Applied Psychological Measurement, 18, 205-215. doi:10.1177/014662169401800302
A psychometric evaluation of 4-point and 6-point Likert-type scales in relation to reliability and validity.
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