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  The extent to which test items or tasks cover a representative sample of the behavioural or conceptual domain they are supposed to measure

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

Criterion-Related Evidence for 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

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

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

Construct-Related Evidence for 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.

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 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 Evidence that the test is unique, that it measures something different from what other available tests measure

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

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 reading ability A measure of “business sense” A measure of “business sense” A measure of musical aptitude A measure of musical aptitude A measure of “social consciousness” or “social responsibility” A measure of “social consciousness” or “social responsibility” A measure of political knowledge A measure of political knowledge

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