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Jun
Mann Whitney U Test Statistic. The critical value for a two-tailed test with n1 17 n2 10 and alpha 05 is 45. Define the following test statistics for samples 1 and 2 where n 1 is the size of sample 1 and n 2 is the size of sample 2 and R 1 is the adjusted rank-sum for sample 1 and R 2 is the adjusted rank-sum of sample 2. It is a non-parametric test that is used to compare two sample means that come from the same population and used to test whether two sample means are equal or not. Usually the Mann-Whitney U test is used when the data is ordinal or when the assumptions of the t-test are not met.
Unlike t-test that compares the means the Mann-Whitney U test compares a randomly selected value from group1 to a randomly selected value from group2. The Mann-Whitney U Test is a statistical test used to determine if 2 groups are significantly different from each other on your variable of interest. The critical value for a two-tailed test with n1 17 n2 10 and alpha 05 is 45. It doesnt matter which sample is bigger. You need to compare the critical value with U minU1 U2 where U1 and U2 are as defined on the webpage Mann-Whitney Test. If the number of observations is such that n xn y is large enough 20 a normal.
The Mann-Whitney U test is approximately 95 as powerful as the t test.
Use statistical tables for the Mann-Whitney U test to find the probability of ob-serving a value of U or lower. It is considered to be the nonparametric equivalent to the two-sample independent t-test. So for example one might compare the speed at which two different groups of people can run 100 metres where one group has trained for six weeks and the other has not. Unlike t-test that compares the means the Mann-Whitney U test compares a randomly selected value from group1 to a randomly selected value from group2. The Mann-Whitney U-Test is a version of the independent samples t-Test that can be performed on ordinal ranked data. Use statistical tables for the Mann-Whitney U test to find the probability of ob-serving a value of U or lower.