Description Usage Arguments Details Value References See Also Examples
This function performs the Levene's test for equality of variance.
1  levene_test(data = NULL, x, groups, alpha = 0.05, modcv = FALSE)

data 
a data.frame 
x 
the variable in the data.frame or a vector on which to perform the Levene's test (usually strength) 
groups 
a variable in the data.frame that defines the groups 
alpha 
the significance level (default 0.05) 
modcv 
a logical value indicating whether the modified CV approach should be used. 
This function performs the Levene's test for equality of variance. The data is transformed as follows:
wij =  xij  mi 
Where mi is median of the ith group. An FTest is then performed on the transformed data.
When modcv=TRUE
, the data from each group is first transformed
according to the modified coefficient of variation (CV) rules before
performing Levene's test.
Returns an object of class adk
. This object has the following fields:
call
the expression used to call this function
data
the original data supplied by the user
groups
a vector of the groups used in the computation
alpha
the value of alpha specified
modcv
a logical value indicating whether the modified
CV approach was used.
n
the total number of observations
k
the number of groups
f
the value of the F test statistic
p
the computed pvalue
reject_equal_variance
a boolean value indicating whether the
null hypothesis that all samples have the same variance is rejected
modcv_transformed_data
the data after the modified CV transformation
“Composite Materials Handbook, Volume 1. Polymer Matrix Composites Guideline for Characterization of Structural Materials,” SAE International, CMH171G, Mar. 2012.
1 2 3 4 5 6 7 8 9 10 11 12  library(dplyr)
carbon.fabric.2 %>%
filter(test == "FC") %>%
levene_test(strength, condition)
##
## Call:
## levene_test(data = ., x = strength, groups = condition)
##
## n = 91 k = 5
## F = 3.883818 pvalue = 0.00600518
## Conclusion: Samples have unequal variance ( alpha = 0.05 )

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