bf_test function

Calculates the Brown-Forsythe test.

bf_test Calculates the Brown-Forsythe test for homogeneity of variance across groups, coefficients, variance-covariance matrix, and degrees of freedom.

bf_test(y, x, formula, data)

Arguments

• y: numeric response variable.
• x: categorical variable.
• formula: A formula object to specify the model as normally used by glm. Use 'factor' to define the grouping variable.
• data: An objects of class milist, created by df2milist, list2milist or mids2milist.

Returns

An object containing:

• fstats F-test value, including numerator and denominator degrees of freedom.
• qhat pooled coefficients from fit.
• vcov variance-covariance matrix.
• dfcom degrees of freedom obtained from df.residual.

Details

The Levene's test centers around means to calculate outcome residuals, the Brown-Forsythe test around the median.

Examples

imp_dat <- df2milist(lbpmilr, impvar="Impnr")
ra <- with(imp_dat, expr=bf_test(Pain ~ factor(Carrying)))

See Also

with.milist

Author(s)

Martijn Heymans, 2021