Manuals/calci/MANNWHITNEYUTEST

MANNWHITNEYUTEST(xRange,yRange,Confidencelevel,Logicalvalue)


  • 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

Spreadsheet
A B
1 20 22
2 15 17
3 25 19
4 35 38
5 17 16

=MANNWHITNEYUTEST(A1:A5,B1:B5,0.05,TRUE)