Obtain variance per group

Obtain variance per group as well as check for the rule of thumb of one group having variance four times bigger than any of the other groups. Variance ratio is calculated as Max / Min.

Usage

nice_var(data, variable, group, criteria = 4)

Arguments

data

The data frame

variable

The dependent variable to be plotted.

group

The group by which to plot the variable.

criteria

Desired threshold if one wants something different than four times the variance.

Value

A dataframe, with the values of the selected variables for each group, their max variance ratio (maximum variance divided by the minimum variance), the selected decision criterion, and whether the data are considered heteroscedastic according to the decision criterion.

See also

Other functions useful in assumption testing: nice_assumptions, nice_density, nice_normality, nice_qq, nice_varplot. Tutorial: https://rempsyc.remi-theriault.com/articles/assumptions

Examples

# Make the basic table
nice_var(
  data = iris,
  variable = "Sepal.Length",
  group = "Species"
)
#>        Species Setosa Versicolor Virginica Variance.ratio Criteria
#> 1 Sepal.Length  0.124      0.266     0.404            3.3        4
#>   Heteroscedastic
#> 1           FALSE

# Try on multiple variables
nice_var(
  data = iris,
  variable = names(iris[1:4]),
  group = "Species"
)
#>        Species Setosa Versicolor Virginica Variance.ratio Criteria
#> 1 Sepal.Length  0.124      0.266     0.404            3.3        4
#> 2  Sepal.Width  0.144      0.098     0.104            1.5        4
#> 3 Petal.Length  0.030      0.221     0.305           10.2        4
#> 4  Petal.Width  0.011      0.039     0.075            6.8        4
#>   Heteroscedastic
#> 1           FALSE
#> 2           FALSE
#> 3            TRUE
#> 4            TRUE