Psych Assessment Test 2

Dependable, repeatable results � necessary but not sufficient for validity

1. Test-Retest Method 2. Parallel/Alternate Forms Method

A. Evaluates temporal stability � consistency over time. Administer test 2 or more times to the same group of individuals. b. Time 1 + Time 2 = Score

C. Advantage � same test, same people d. Disadvantage � characteristic might change, time interval. e. Carryover Effects � being tested on one occasion can affect second occasion or may create desire to be consistent. Optimal time 2-3 weeks.

A. Similar to test/re-test, but form of test changes to an alternate form but still measures the same stuff in content. b. Compare Correlation between test A & B. c. High Correlation = Related

Extent to which items are interrelated in the cumulative. Do items �hang together�

1. Split-Half Reliability 2. Coefficient Alpha (Cronbach) α or jesus fish

A. Divide test if half and score both parts, do they correlate. b. Odd/Even Method � sum of #�s 1,3,5,7,9 etc. so order of items is not as important.

C. Advantages � use same items at the same time d. Disadvantage � different results based on how you split the times.

A. Better measure than split half. b. Measures internal reliability c. Has all advantages as split half d. Depends on i. Average intercorrelation of items should be high, higher average intercorrelation = higher α ii. Number of items 0 �itmes = �reliable e. Desireable Test Results i. Should exceed .70 ii. Desireable to be above .90 iii. Self-Esteem Scale = .832

Unwanted variability

Observed Score � true score + error (deviation) Errors are random +/- s2 = Ration of true score to true score variability True Score + Error

SEM is standard deviation of observed scores Exresses the expected error or margin of error �average error�

To get 95% score calc SEM * 1.96 & calc range

Used to build reliabilty into the test �analyses of individual items of test. -Goal � to produce reliable test which makes it more likely will have a have valid test. -Item Reliability - Does item contribute to the reliability of the test. �Hang Together� with other items. -Item total Correlation � score of item compared to score on other items.