createGroup function

Create Mapping Matrix of DIF Groups

This function automatically create a mapping matrix based on the existing DIF inducing covariates.

createGroup(backInfo, idxUsed = NULL, contMethod = c("mean", "median"))

Arguments

• backInfo: A matrix of person background information (e.g., gender, country, age, etc);
• idxUsed: The column number of backInfo that is used for creating the mapping matrix.
• contMethod: The method of how to handle a continuous variable (e.g., mean, median). This parameter is passing a function used to split the variable into binary. The default is mean.

Returns

A binary matrix that maps respondents to the groups that the respondents belongs to.