Manuals/calci/MANNWHITNEYUTEST

MANNWHITNEYUTEST (XRange,YRange,ConfidenceLevel,NewTableFlag)


  • is the array of x values.
  • is the array of y values.
  • is the value between 0 and 1.
  • is either TRUE or FALSE.


Description

  • This function gives the test statistic value of the Mann Whitey U test.
  • It is one type of Non parametric test.It is also called Mann–Whitney–Wilcoxon,Wilcoxon rank-sum test or Wilcoxon–Mann–Whitney test.
  • Using this test we can analyze rank-ordered data.
  • This test is alternative to the independent-sample, Student t test, and yields results identical to those obtained from the Wilcoxon Two Independent Samples Test.
  • This test is used to compare differences between two independent groups when the dependent variable is either ordinal or continuous, but not normally distributed.
  • Mann whitey u test is having the following properties:
  • 1.Data points should be independent from each other.
  • 2.Data do not have to be normal and variances do not have to be equal.
  • 3.All individuals must be selected at random from the population.
  • 4.All individuals must have equal chance of being selected.
  • 5.Sample sizes should be as equal as possible but for some differences are allowed.
  • Suppose the two groups of the populations have distributions with the same shape it can be viewed as a comparison of two medians.With out the assumption the Mann-Whitney test does not compare medians.
  • To find statistic value of this test the steps are required:
    • 1.For the two observations of values, find the rank all together.
    • 2.Add up all the ranks in a first observation.
    • 3.Add up all the ranks in a second group.
    • 4.Select the larger rank.
    • 5.Calculate the number of participants,number of people in each group.
    • 6.Calculate the test statistic: 
  • where   and   are number of participants and number of people.
  •   is the larger rank total.  is the similar value of  .
    • 7.State Result: In this step we have to take a decision of null hypothesis either accept or reject depending on the z value using critical value table.
    • 8.State Conclusion: To be significant, our obtained U has to be equal to or LESS than this critical value.

Example

X Y
87 71
72 42
94 69
49 97
56 78
88 84
74 57
61 64
80 78
52 73
75 85
0 91
  1. =MANNWHITNEYUTEST(A1:A12,B1:B12,0.05,true)

Mann Whitney U Test

Ranks
x y
20 10
11 2
23 9
3 24
5 15.5
21 18
13 6
7 8
17 15.5
4 12
14 19
1 22
Ranks 139 161
Median 73 75.5
n 12 12
Results
U1 83
U2 61
U 61
E(U1) 150
E(U2) 150
E(U) 72
StDdev 17.320508075688775
  0.05
z -0.6350852961085883
p 0.5253738185447192

Related Videos

MannWhitney U Test

See Also

References