If KR-20 reliability of a test is found to be low, then which of the following could be the most important reason ?
MH SET - 2020, SET Exam - 2020,
Answer: A
The most important reason for a low KR-20 is inadequate content sampling.
KR-20 is a measure of internal consistency for tests with right-wrong items. It reflects how far the items measure the same thing. If the items sample heterogeneous content, or the item sample is poor, the items do not correlate well with each other and KR-20 falls; content sampling is the main source of error variance it detects.
Interscorer agreement is irrelevant to KR-20, which is used for objectively scored items. Items that are too hard reduce score variance, but that is a narrower effect, and a longer test raises reliability, as the Spearman-Brown formula shows, so it cannot explain a low value.
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