HomogeneityOfRegressionSlopes: Checking homogeneity of regression slopes

In yhhc2/ancovall: Package that automates the process of doing ANCOVA on a large number of dependent variables

Description

Returns information that can be used to determine if the homogeneity of regression slopes, an assumption for ANCOVA, is met.

Usage

HomogeneityOfRegressionSlopes(
  inputted.data,
  dependent.variable,
  independent.variable,
  covariates
)

Arguments

inputted.data	A dataframe
dependent.variable	A string that specifies the column name of the column to use as the dependent variable. Column must be numeric.
independent.variable	A string that specifies the column name of the column to use as the independent variable. Column can be numeric or factor. If it's a factor, then it can only have two levels.
covariates	A vector of strings that specifies the columns names of the columns to be used as covariates. Columns can be numeric or factor. If it's a factor, then it can only have two levels.

Details

To test homogeneity of regression slopes, interaction terms need to be added and the p-value should be assessed. If the p-value is significant for any interaction term, then this means the assumption of homogeneity of regression slopes is not met.

Value

A matrix with two rows. The first row specify what the values are in the second row. The second row: The first element is the formula used to evaluate p-value of interaction terms. The remaining elements are the p-values for each interaction term.

Examples

dependent.col <- c(10.1, 11.3, 12.1, 13.7, 14.2, 1.6, 2.3, 3.2, 4.1, 5.3)
independent.col <- as.factor(c(1, 1, 1, 1, 1, 0, 0, 0, 0, 0))
covariate.one.col <- c(1, 2, 3, 4, 5, 1, 2, 3, 4, 5)
covariate.two.col <- as.factor(c(1, 0, 1, 0, 1, 0, 1, 0, 1, 0))

inputted.data <- data.frame(dependent.col, independent.col, covariate.one.col,
                            covariate.two.col)

results <- HomogeneityOfRegressionSlopes(inputted.data, "dependent.col",
                                         "independent.col",
                                         c("covariate.one.col", "covariate.two.col"))

results

yhhc2/ancovall documentation built on Dec. 23, 2021, 7:19 p.m.