KR-21 provides a lower limit for the computed value of KR-20. KR-20 is equivalent to coefficient alpha when a test is composed of dichotomous items scored 0 or 1. Therefore, KR-21 coefficients, computed from simple summary statistics, can be used in cases in which journal authors do not provide the test score reliability. Use of KR-21 in these cases will provide the reader with a lower limit for the value of KR-20.