Extended Tables of the Wilcoxon Matched Pair Signed Rank Statistic

Abstract A table of critical values of the Wilcoxon Signed Rank Statistic is presented for N = 4(1)100 pairs of observations at one-tail probability levels of .00005, .0005, .0025, .005 (.005) .025, .050 (.025) .150, and .20 (.05) .45. Probabilities were computed accurately to at least 6 digits, regardless of the location of the decimal point. Therefore, all critical values are correct as tabled. Normal approximation probabilities were found to be biased, too small at the .05 level but too large at the .005 and .0005 probability levels. Approximation errors were less than 10% for all N > 35 for the .05, .025, and .005 one-tail probability levels; but this degree of accuracy was not achieved at the .0005 level for N = 100.