A clarification of the effects of rapid guessing on coefficient alpha: A note on Attali’s “Reliability of Speeded Number-Right Multiple-Choice Tests”
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Attali (2005) recently demonstrated that Cronbach’s coefﬁcient a estimate of reliability for number-right multiple-choice tests will tend to be deﬂated by speededness, rather than inﬂated as is commonly believed and taught. However, random responses on low-stakes tests may be due to lack of effort rather than speededness. In real data, we found that random responses tended to result in more pairs of inflated than deflated item covariances, inflating estimates of reliability.
Wise, S. L. & DeMars, C. E. (2009). A clarification of the effects of rapid guessing on coefficient alpha: A note on Attali’s “Reliability of Speeded Number-Right Multiple-Choice Tests”. Applied Psychological Measurement, 33, 488-490.