Validity and Reliability

1. Validity

1.1. Does the test measure what we say it measures?

1.2. Construct validity - do test scores correspond to scores on other variables as predicted by the current rationale or theory?

1.3. Content validity - systemic comparison of a test item with instructional objectives

1.4. Criterion-related validity - correlation of test scores with an external standard

2. Interpretation

2.1. Principles of Interpretation

2.2. what is the purpose of the test?

2.3. what is the strength of the validity coefficient?

2.4. what is the relevance or reliability of the standard?

3. Reliability

3.1. Is the test reliable based on the stability of test scores?

3.2. Test-retest estimates - administer the same test twice to the same group of students

3.3. Alternate-form estimates - administer two alternate forms of a test to the same group of students

3.4. Internal consistency estimates - odd-even estimates or item-total correlations

4. Interpretation

4.1. Principles of Interpretation

4.2. Length of test affects test score reliability

4.2.1. longer the test, reliability increases

4.3. group variability affects test score variability

4.3.1. when group variability increases reliability increases

4.4. scoring reliability limits test score reliability

4.4.1. when scoring reliability decreases test reliability decreases

4.5. Difficulty of questions affects test score reliability

4.5.1. Questions are too easy or too hard, reliability decreases