1. Test Development Test conceptualization Test construction Test tryout
Item analysis
Test revision

2. Test construction
Scaling: process of setting rules for assigning numbers in measurement; how numbers are assigned to different amounts of the construct being measured
Scaling methods based on objectives of test

3. Scaling Methods Rating scales:less to more continuum
Summative scale: ratings on each item are summed for total
Likert scale: 5 or 7 response alternatives, usually agree/disagree continuum
Guttman scale: weaker to stronger expressions; all respondents who agree with stronger statements also agree with milder statements
Ordinal measurement

4. Test Tryout What is a good item? Item Analysis
Item-difficulty index: proportion of total testtakers who get item right (p=0 to 1)
Higher the p, easier the item

5. Good items (cont.)
ITEM-VALIDITY INDEX: degree to which a test measures what it intends to
Function of the item-score standard deviation & correlation between item and criterion
Item-validity index=

6. Good items (cont.)
ITEM-RELIABILITY INDEX: indication of the internal consistency of the test
Product of the item-score standard deviation and the r between the item score and total test score

7. Good items (cont.)
ITEM-DISCRIMINATION INDEX: Does the item differentiate (discriminate) between high scorers and low scorers?
Difference between the proportion of high scorers answering an item correctly and the proportion of low scores answering the item correctly
The higher the d value the greater # of high scorers answering correctly; - d value is a red flag
Range from -1 to +1
Highest & lowest 27%

8. Good items (cont.)
ANALYSIS OF ITEM ALTERNATIVES: How many test takers chose each alternative on multiple-choice test?
Are there patterns?
Any one distractor that attracts answers?
How do high scorers and low scorers compare?

9. Guessing Correction formula:
Assumes all alternatives are equally plausible and that items can be divided into those an examiner knows perfectly and those he/she doesn’t know.
Ex. Estimated # correct = Right - Wrong/k-1
(k = 3 of alternatives)
ex /3=45