# Discussion 2 week 4

Validity and Reliability

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Discussion 2 week 4

## 2. VALIDITY- Denotes the extent to which an instrument is measuring what it is supposed to measure.

### 2.2. Criterion- Related Validity Evidence Criterion- A method for assessing the validity of an instrument by comparing its scores with another criterion known already to be a measure of the same trait or skill. Criterion-related validity is usually expressed as a correlation between the test in question and the criterion measure. The correlation coefficient is referred to as a validity coefficients.

2.2.1. Concurrent Criterion - Related Validity Evidence- The extent to which a procedure correlates with the CURRENT behavior of subjects

2.2.2. Predictive Validity Evidence- The extent to which a procedure allows accurate predictions about a subject’s FUTURE behavior

## 3. Reliability- The consistency of measurements. If a test item is reliable, it can be correlated with other items to collectively measure a construct or content mastery.

### 3.1. Methods of Estimating

3.1.1. Test-Retest or Stability - Give the same test twice to the same group with any time interval between tests

3.1.2. Alternate forms or Equivalence - (similar in content, difficulty level, arrangement, type of assessment, etc.)Give two forms of the test to the same group in close succession.

3.1.3. Internal Consistency- items ought to be correlated with each other,

3.1.3.1. Split-half method- involves splitting the test into two equivalent halves and determining the correlation between them. This can be done by assigning all items in the ﬁrst half of the test to one form and all items in the second half of the test to the other form. However, this approach is only appropriate when items of varying difﬁculty are randomly spread across the test

3.1.3.2. Kuder-Richard Methods- These methods measure the extent to which items within one form of the test have as much in common with one another as do the items in that one form with corresponding items in an equivalent form. The strength of this estimate of reliability depends on the extent to which the entire test represents a single, fairly consistent measure of a concept.