Mann Whitney U Test

 

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Non-Parametric Test (DR SEE KIN HAI) Mann-Whitney U Test (Mann-Whitney Rank-Sum Test ) (For two independent samples- You use this test if the data violated the assumptions for  using the independent sample t t - test)

Before you can perform this test, the data must fulfill the assumptions below (although not so stringent as parametric technique). 1. Data randomly collected from the population. 2. Variance for the the data distribution is equal. 3. Independence of samples. 4. Test

 H o :

Example:

there is no significant difference between the 2 independent samples.

A test on Algebra was given to 30 students after after a lesson in this topic of 

Mathematics. Student gender was recorded as 1 = male and 2 = female.

You are to 

determine if there are gender differences in their scores for Algebra. (Assuming that the data  has violated the assumption of the use of independent sample t-test) 

 

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How to run Mann-Whitney U Test 1. Select [Analyze] then [Nonparametric Tests] then [Legacy Dialogs] Dialogs] and [2 Independent Samples…] to open the dialogue box below.

2. Move [Algebra] into [Test Variable List:] box and [Gender] into [Grouping Variable] box and select [Define Groups..] Type 1 for male, and 2 for female, then [Continue] and [OK] The groups are defined as 1, 2 or male and female

 

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Interpreting the output for the Mann-Whitney U-test The Mean Rank given to [Algebra] for the first group (1=male) is 8.07 and the average rank given to the second group (2=female) is 22.93. This means that the mean scores for female is higher than the male

The basic Mann-Whitney statistic, the Uvalue is 1.000, which is statistically significant at the 0.000 level.

The  Z   –  value of - 4.658 is significant at  – value 0.000 level. This is the value of MannWhitney test when a correction for tied ranks has been applied. This has not altered the significance level from 0.000b to 0.000.

Reporting the output for the Mann-Whitney U-test The Mann-Whitney U-test found that the Algebra test scores for female is significantly higher  than the male (U = 1.000,

 N 1 =15,  N 2

=15, two-tailed p = p = 0.000).

COURSEWORK

  An English language teacher wanted to know whether there is any significant difference in male and female students’ English Test. Test. She has administered an English language test to a group of 60 students. 10 male and 10 female students were randomly randomly selected from the 60 students. (Assume that the data has violated the assumption for using independent sample t - test). - test).

 

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