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Validity

Validity. Face Validity. The extent to which items on a test appear to be meaningful and relevant to the construct being measured. Content-Related Evidence for Validity. The evidence that the content of a test represents the conceptual domain that the test is designed to cover

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Validity

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  1. Validity

  2. Face Validity • The extent to which items on a test appear to be meaningful and relevant to the construct being measured

  3. Content-Related Evidence for Validity • The evidence that the content of a test represents the conceptual domain that the test is designed to cover • The extent to which test items or tasks cover a representative sample of the behavioural or conceptual domain they are supposed to measure

  4. Concepts Related to Content Validity • Construct Underrepresentation • Failure to capture important components of the construct • Construct-Irrelevant Variance • Scores are influenced by factors irrelevant to the construct

  5. Criterion-Related Evidencefor Validity • The evidence that a test score corresponds to an accurate measure of interest, called the “criterion” • The criterion is a direct & independent measure of that which the test is supposed to predict

  6. Validity Coefficient • Correlation between test & criterion • Rarely greater than .6 • Considered satisfactory if in the range of .3 to .4

  7. Concerns About Evaluating Validity Coefficients • Changes in cause of relationships • Meaning of criterion • Subject population • Sample size • Confusion of criterion with predictor • Restricted range of predictor & criterion • Evidence for validity generalization • Differential prediction

  8. Construct-Related Evidencefor Validity • A CONSTRUCT is a theoretical entity used to explain and organize response consistencies • A process used to establish the meaning of a test through a series of studies • Researcher simultaneously defines a construct & develops a measure of that construct • Then looks at how the measure relates to other measures, behaviours, etc.

  9. Types of Construct-Related Evidence • Convergent evidence • Evidence that the test correlates highly with other tests, behaviours that supposedly measure the same or related construct • Discriminant evidence • Evidence that the test is unique, that it measures something different from what other available tests measure

  10. Ways of Establishing Convergent Validity • Correlation with measure designed to measure same or related construct • Age differentiation • Experimental interventions • Known groups

  11. Class Exercise • Using the four methods (correlation with other measures, age differentiation, experimental intervention, known groups), think of at least 2 ways to validate each of the following: • A measure of reading ability • A measure of “business sense” • A measure of musical aptitude • A measure of “social consciousness” or “social responsibility” • A measure of political knowledge

  12. Relationship Between Reliability & Validity • A test should not correlate more highly with any other variable than it correlates with itself • Maximum validity coefficient (R12max) between 2 variables is equal to the square root of the product of their reliabilities

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