R. Clifford Blair, James J. Higgins, A Comparison of the Power of Wilcoxon's Rank-Sum Statistic to That of Student's t Statistic under Various Nonnormal Distributions, Journal of Educational Statistics, Vol. 5, No. 4 (Winter, 1980), pp. 309-335
No takes yet. Share an insight, caveat, or question.
Blair et al. (1980) studied this question.