Split-half reliability

Split half reliability is estimated by correlating the pairs of scores obtained from equivalent halves of test administered only once.
In this simplest of internal consistency approach, a single test is viewed as composed of two parts measuring in some thing.
The split half approach to reliability is useful in cases where the test retest method is forbiddingly expensive or where retesting is potentially misleading.
It is apparent the split half reliability provides a measure of consistency with regard to content or item sampling.
Temporal stability of the scores does not enter into such reliability.
It is sometimes called a coefficient of internal consistency.
Types of creating two equivalent halves of the test;
1. If the test is long the best method is to divide the items randomly in two halves.
For ease in computing score for the different halves, some people prefer to calculate a score for the first half of the items and another score for the second half.
Although convenient, this method can cause problems when item on the second half of the test are more difficult than items on the first half.
• If the items get progressively more difficult, then the best method is to use odd-even system, comparing score on the odd and even items of the test.
If the item were originally arranged in an approximate order of difficult, such a division yield very nearly equivalent half-score.
Computation of Split-Half;
To estimate the reliability of the test, we could find the Pearson product moment correlation (r) between score on the two equivalent halves of the test.