a character vector containing the variable names where the marginal effect
refers to the impact of a discrete change on the outcome. For example, a factor variable.
call
the matched call.
Details
If both robust=TRUE and !is.null(clustervar1) the function overrides the robust
command and computes clustered standard errors.
References
William H. Greene (2008). Econometric Analysis (6th ed.). Prentice Hall, N.Y. pp 770-787.