Relabels the attribute levels to create a new design candidate. For example, if the column contains the levels (1, 2, 1, 3, 2, 3) and 1 and 3 are relabeled, then the column becomes (3, 2, 3, 1, 2, 1), i.e. 1 becomes 3 and 3 becomes 1.
A vector of attribute levels
Will randomly sample 2 attribute levels that will be relabeled and the relabeling is done independently for each column, which implies that the same attribute will be relabeled differently depending on which alternative it belongs to.
Hensher, D. A., Rose, J. M. & Greene, W., 2005, Applied Choice Analysis, 2nd ed., Cambridge University Press