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Description:
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The main focus of this investigation is to verify the robustness of validity of these tests . By robustness of validity , it is meant the stability of the Type I error rate for small designs as well as conditions under which some of the underlying assumptions are violated . For methods that produce valid tests , further investigations with respect to power are meaningful . Since many nonparametric methods use large sample approximation theory , it may be expected that these methods will perform better as n , the number of blocks , increases . As the number of treatments , p , gets larger , it becomes harder to reject the null hypothesis since this increases the critical value . As we will see , some design structures make rejection of the null hypothesis impossible for certain methods . The methods of interest include the sign statistic , signed rank statistic , rank sum statistic (Aligned Rank statistic using separated rankings and uniform scores ) . Aligned -Rank Transform , Within -Block ranking , and least squares . |