1. Reliability n Consistent n Dependable n Replicable n Stable

2. Threats to reliability n Construction n Administration (tester, testee, environment) n Scoring n Interpretation

3. Two Administrations n Test/retest same test - same group n Parallel/Alternate forms different tests - same group

4. One Administration Internal consistency One test - one group - one administration n Split Half first/second or odd/even halves???? Spearman-Brown formula n Statistical estimation Kuder-Richardson Formula 20 (KR20) Cronbach alpha (alpha coefficient) n (factor analysis)

5. Reliability coefficient n 0.00 - 1.00 n higher is better n score is relative, not absolute

6. Inter-rater reliability n Consensus n Percentage of agreement n Kappa statistic (2 or many raters)

7. Project homework n Which approach (and why) would you use to determine the reliability of your measure?