Lab 4: Alpha and Standard Error of Measurement. Reliability. Reliability refers to consistency Types of reliability estimates Test-retest reliability Interobserver (or interrater) reliability Internal consistency Alpha measures the consistency of responses across items.
Extraversion scale: k = 10
Extraversion scale: rij = .46
1. Report the standardized alphas for all five IPIP scales at Time 2. Also report the average inter-item correlation and number of items. (2 point)
2. Imagine that the average inter-item correlation for a scale is .40. Compute the standardized alphas for tests with the following numbers of items: 5, 10, 15, 20, 25. (3 points)
3. Report the SEM for all 5 IPIP scales at Time 2 with interpretation. (3 points)
4. Report the confidence interval for the mean conscientiousness at time 2 at the 96% CI with interpretation. (2pts.)