Chapter Questions
What is the difference between an item difficulty index and an item discrimination index?
How do you know whether to calculate the discrimination index (which contrasts extreme groups), the biserial correlation, or the point-biserial correlation coefficient as your item discrimination statistic?
How do you decide which external criterion to use when computing an itemcriterion index?
Is there ever a time when a $.25 p$ value is good? How about a $1.00 p$ value?
. Will your criteria for evaluating your item difficulty and discrimination indexes change if a test is norm referenced versus criterion referenced?
Will your criteria for evaluating your item difficulty and discrimination indexes change as the format of the item changes (e.g., true-false; three-, four-, or fiveoption multiple choice; Likert scaling)?
Oftentimes in a classroom environment, you might have more students (subjects) than you have items. Does this pose a problem for interpreting your item analysis statistics?
What corrections, if any, might you make to items $1,2,4,5$, and 8 in Table 12.2?