Reliability & Validity Measurement Quality Reliability & Validity

Questionnaires Descriptive Questionnaires Analytical Questionnaires Typically asks about factual information that describes a person (e.g., census) Analytical Questionnaires Asks about information related to attitudes or opinions (e.g., political polls) Instruments (a.k.a., Inventories) Standardized measures of constructs (e.g., personality traits)

Constructs Construct A hypothetical attributes or mechanisms that help explain/predict in a theory Latent Construct A construct defined by other constructs

Latent Construct A construct defined by other constructs Organized Conscientious Responsible Practical Self-Control

Reliability The stability or consistency of a measurement Test-Retest Procedures Involves administering the same measure to the same people twice

Reliability Internal Reliability (Split-half Reliability) The stability or consistency of a measurement Test-Retest Procedures Involves administering the same measure to the same people twice Internal Reliability (Split-half Reliability) Involves assessing the consistency of multiple items measuring the same construct within a particular measure

Reliability What improves reliability? More Items/Measures Consistent Conditions

Validity Degree to which the measurement measures a theoretical construct

Face Validity The degree to which it looks valid

Concurrent Validity Established when scores from a new measure are directly related to scores obtained on an established measure

Validity Face Validity Concurrent Validity Convergent Validity When two instruments measuring the same thing are correlated Divergent Validity When two measures of similar constructs are less related than measures of the same construct

Establishing validity of measure of Self-Control (SCS) Convergent Validity (r = .65) DIvergent Validity (r = .48) Establishing validity of measure of Self-Control (SCS)

Validity Face Validity Concurrent Validity Convergent Validity Discriminant Validity Predictive Validity When a test is shown to be effective at estimating a performance on some established criteria (outcome)

Predictive Validity Eating Disorder Alcoholism GPA Self-Control Scale -.36 -.31 .19

Reliability - Validity Reliable, but not valid Valid… it must be reliable