What range of difficulty should the items cover?

The range of item difficulty must be sufficient to allow for meaningful differentiation of examinees at both extremes.

A ceiling effect is observed when significant numbers of examinees obtain perfect or near perfect scores. The problem with ceiling effect is that distinctions between high scoring examinees are not possible, even though these examinees might differ substantially on the underlying trait measured by the test.

A floor effect is observed when significant numbers of examinees obtain scores at or near the bottom of the scale. For example, the WAIS-R has a serious floor effect in that it fails to discriminate between moderate, severe and profound levels of mental retardation-all person with significant development disabilities fail to answer virtually every question.


Describe the item formats of test

When it comes to the method by which psychological attributes are to be assessed, the test developer is confronted with dozens of choices. There are 5 types of item formats-
a. Multiple choice; for group-administered test of intellect or achievement, the technique of choice is the multiple choice question.

Advantage of MCQ;
 Properly constructed items can measure conceptual and factual knowledge
 Permit quick and objective machine scoring
 Fairness.
Disadvantages
 Difficulty of writing good distracter options
 Guesses
The guidelines for writing multiple choice items
 Choose words that have precise meanings.
 Avoid all information needed for response selection.
 Include all information needed for response selection
 Put as mush of the question as possible in the stem.
 Do not take stems verbatim from textbooks
 Use options of equal length and parallel phrasing
 Use ‘none of the above’ and ‘all of the above’ rarely.
 Minimize the use of negative such as “not”
 Avoid the use of nonfunctional words
 Avoid unessential specificity in the stem
 Avoid unnecessary clues to the correct response
 Submit items to others for editorial security


b. Matching; Matching questions are popular in classroom testing, but suffer serious psychometric shortcomings.
Disadvantages
 Responses are not independent missing one match usually compels the examinee to miss another.
 The options must be very closely related or the question will be too easy.

c. Short answer objective item; for individual administered test, the procedure of choice is the short-answer objective item.
Advantage;
 Simplest and most straightforward
 Best reliability and validity
d. True/false; Personality test often use true/false questions because they are easy for subjects of understand.
Advantage
 Simple to answer the true or false
Disadvantages
 Answer may reflect social desirability rather than personality
e. Forced choice methodology; an alternative format designed to counteract this problem is the forced choice methodology, where the examinee must choose between two equally desirable options.