An instrument that measures mathematics knowledge, reading comprehension, and computation skills provides four measures, one score for each scale and an overall score. Which of the following is likely regarding the properties of the scores?
A) The reliabilities of the individual scores are lower than the overall score.
B) The reliabilities of the individual scores are higher than the overall score.
C) The reliability of the overall score is the average of the reliabilities of the individual scores.
D) The reliability of the overall score is the sum of the reliabilities of the individual scores.

Question

Quizplus · Accepted Answer

It is likely that the reliabilities of the individual scores (mathematics, reading comprehension, computation) are higher than the overall score because the individual scores have a more specific focus and thus may have fewer sources of error. The overall score will likely have more sources of error due to the combination of the different scales. However, this is not always the case, as it depends on the specific test and how the scores are calculated.

An Instrument That Measures Mathematics Knowledge, Reading Comprehension, and Computation