PSYCHOMETRICS
Procedures for Estimating Reliability
Split-half methods rc.06.1
The CTT identifies 3 situations in which we can have parallel measures:
1. The Parallel test (parallel forms)
2. Test-Retest
3. Split-half procedure
PARALLEL TEST ( Coefficient of Equivalence): 2 tests or forms that have the
same format and the same content. Once we have the two parallel forms, we apply
them to the same sample and we estimate the Pearson correlation between the
observed score of each two forms.
TEST-RETEST (Coefficient of Stability): Apply the same test twice to the same
sample (two different times) and estimate the Pearson correlation between the
observed scores of the two measurements.
SPLIT-HALF METHOD (Coefficient of homogeneity): Split the items of the test
in two (comparable) forms, get the observable total score of each half and:
