Probability estimators developed previously by the authors have been used to compare unbiased estimates of the shape parameters (Weibull modulus) from two distributions by the linear regression method for thirteen sample sizes ranging from 10 to 100. Percentiles of the ratio of two estimated Weibull moduli for various confidence levels have been developed. The use of these percentiles for hypothesis testing, i.e., comparison of the two Weibull moduli is demonstrated by using datasets from the literature. (C) 2011 Elsevier B.V. All rights reserved.