# Validity & Reliability

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Validity & Reliability

## 1. Reliability

### 1.1. Test-Retest or Stability

1.1.1. Reliability are obtained by administering the same test twice to the same group of individuals, with a a small time interval between testing, and correlating the scores.

### 1.2. Alternate Forms or Equivalence

1.2.1. Are obtained by administering two alternate or equivalent forms of a test to the same group and correlating their scores.

### 1.3. Internal Consistency

1.3.1. These estimates should be used only when the test measures a single or unitary trait.

### 1.4. Split-half methods

1.4.1. Divide a test into halves and correlate the halves with one another. Because these correlations are based on half test, the obtained correlations underestimate the reliability of the whole test.

### 1.5. Kurder-Richardson

1.5.1. Determine the extent ot which the entire test represents a sing fairly consistent measure of a concept.

### 1.6. Problems with internal consistency

1.6.1. Estimates tend to yield inflated reliability estimates for speeded tests.

## 2. Validity

### 2.1. Content

2.1.1. Comparing test items with instructional objectives to see if they match.

### 2.2. Criterion-Related

2.2.1. Correlating test scores with external standards or criterion to obtain numerical estimate.

2.2.1.1. Concurrent

2.2.1.1.1. Determined by correlating test scores with a criterion measure collected at the same time.

2.2.1.2. Predictive

2.2.1.2.1. Determined by correlating test stores with a creterion measure collected after a period of time has passed.

### 2.3. Construct

2.3.1. Determined by finding whether test results correspond with scores on other variables as predicted by some rationale or theory.