A Math Test Developer Is Interested in Deriving an Index

Multiple Choice

A math test developer is interested in deriving an index of the difficulty of the average item for his math test.As his consultant on test development,you advise him that this index could be obtained by:

A) identifying the item deemed to be average in difficulty and then deriving an item-difficulty index for that item.
B) averaging the item-difficulty indices for all test items and then dividing by the total number of items on the test.
C) dividing the total number of items on the test by the average item-difficulty index.
D) raising that very same question to a more knowledgeable test development consultant.