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Result Reality Difference Exists between Groups in Population No Difference Exists between Groups in Population Accept null hypothesis Type II error (β) True Reject null hypothesis True Type I error (α) χ2 Fisher exact Wilcoxon signed-rank Kruskal-Wallis Mann-Whitney U Spearman rank correlation - Table 3:
Results of search of AJNR articles with the term “no significant difference” on August 8, 2006
n % Study design Prospective 28 70 Retrospective 10 25 Indeterminate* 2 5 Study type Lab/Animal 7 17.5 Statistics Parametric 22 55 Nonparametric 11 27.5 Both 7 17.5 Clearly indicated power 3 7.5 Raised the issue of power 6 15 Provided confidence intervals for results 2† 5 * Study design could not be determined from the Methods section.
† Neither of these studies indicated the power of their analysis