Manuals/calci/LEVENESTEST

LEVENESTEST(xRange,ConfidenceLevel,LogicalValue)


  • is the set of values for the test.
  • is the value from 0 to 1.
  • is either TRUE or FALSE.

Description

  • This function used to test the Homogeneity of variances.
  • Levene's test is used to test the Samples have equal variances.
  • Equal variances across samples is called homogeneity of variance or homoscedasticity.
  • To do the Levenes test we need the following assumptions:
  1.The Samples from the populations are independently of one another. 
  2. The population under consideration are Normally Distributed. 
  • For three or more variables the following statistical tests for homogeneity of variances are commonly used:
   1.Levene's Test.
   2.Bartlett Test.
  • Levene's test is an alternative to the Bartlett test.
  • If the data surely is of normally distributed or nearly to normally distributed then we can use the Bartlett test.
  • The Levene's test is defined as
 .
 =Not all of the variances are equal. 
  • Normally there are three versions of the Levenes test.
  • There are
  • 1.Use of Mean.
  • 2.Use of Median.
  • 3.Use of 10% of Trimmed Mean.
  • The Levene test statistic is:

 .

    • where   is the result of the test.
    •   is the number of different groups to which the sampled cases belong.
    •   is the total number of cases in all groups.
    •   is the number of cases in the   group.
    •   case from the   group.
  • Zij is satisfying the one of the following conditions:
  • 1. ,Where   is the Mean of the   subgroup.
  • 2. ,Where   is the Median of the   subgroup
  • 3. ,Where   is the 10%Trimmed Mean of the   subgroup.
  • Levene's Testing Procedure:
  • 1. checking the assumptions.
  • 2.State the Null(H0) and alternative(H1) hypothesis.
  • 3.Decide on the Significance level (α).
  • 4.Finding the Critical value and Rejection Region.Here  , .
  • 5.Compute the Levenes statistic using the formula.
  • 6.Then decision of the value of the test statistic,W is falls in the rejection region or if p-value ≤ α, then reject  .Otherwise, fail to reject  . For the computation p-value we have to use the value of   and  .
  • 7. Finally we have to conclude that the rejection of   or fail to rejection   according to the test statistic at the significance level.

Example

Spreadsheet
A B C
1 11 21 28
2 12 20 36
3 14 18 48
4 17 14 51
5 19 10 20
6 22 17 43
7 24 25 24
  1. =LEVENESTEST(A1:C7,0.25,TRUE)= 1.740658517666