Used to assess the consistency of the results of two tests constructed in the same way from the same content domain.
One major problem with this approach is that you have to be able to generate lots of items that reflect the same construct, which is often no easy feat. Futhermore, this approach makes the assumption that the randomly divided halves are parallel or equivalent. Even by chance, this will sometimes not be the case.
Internal Consistency Reliability
Used to assess the consistency of results across items within a test.Internal-consistency measures:
Average Inter-item Correlation, Average Item-Total Correlation, Split-Half Reliability and Cronbach’s Alpha.