1. Item writing

2. Guidelines for item writing
1. Define clearly what you want to measure. To do this, use substantive theory as a guide and try to make items as specific as possible. 2. Generate an item pool. Theoretically, all items are randomly chosen from a universe of item content. 3. Avoid exceptionally long items. Long items are often confusing or misleading.

3. 4. Keep, the leνel of reading difficulty appropriate for those who will complete the scale. 5. Avoid ‘'double-barreled" items that convey two or more ideas at the same time. “I vote Democratic because I support social programs.“??? 6. Consider mixing positively and negatively worded items. The respondents will tend to agree with most items. The CES-D uses mostly negatively worded items (such as “I felt depressed.”). The CES-D also includes items worded in the opposite direction (“I felt hopeful about the future").

4. Item formats
Dichotomous
Polychotomous
Likert
Q-sort

5. Dichotomous
The dichotomous format offers two alternatives for each item. (True/False, Yes/No)
The mere chance of getting any item correct is 50%. Thus, to be reliable, a true-false test must include many items.
Overall, dichotomous items tend to be less reliable, and therefore less precise than some of the other item formats.

6. Polychotomous
The polytomous format (sometimes called polychotomous) resembles the dichotomous format except that each item has more than two alternatives.
When taking a multiple-choice examination, you must determine which of several alternatives is “correct." Incorrect choices are called distractors.
It is usually best to develop three or four good distractors for each item. Well-chosen distractors are an essential ingredient of good items.

7. The formula to correct for guessing on a test
If each test item has four choices, the test taker would be expected to get 25% of the total number of items correct. If the test items had three choices, then a 33.33% rate of success would be expected. Because test takers get some “correct" answers simply by guessing, a correction for guessing is sometimes used.
The formula to correct for guessing on a test is

8. Likert format
One popular format for attitude and personality scales requires that a respondent indicate the degree of agreement with a particular attitudinal question.
Five-point, six-point, seven-point
Often treated as Interval scale. Factor analysis, Item discriminability

9. Q-sort
The Q sort can be used to describe oneself or to provide ratings of others.
A subject is given statements and asked to sort them into nine piles.
E.g., Give observers 100 statements about personal characteristics. The statements are sorted into piles that indicated the degree to which they appeared to describe a given person accurately.
California Q-sort

11. Questions Can you make some examples of the following item formats?
dichotomous
polychotomus
Likert
In a dichotomous format test with 10 items, you got 5 right responses. How good were you on the test? Use the correction for guessing formula.