I have a dataset that contains factors corresponding income ranges of sampled persons, like people with factor 1 earn between 10,000 to 20,000, 2 between 20,000 to 30,000 . I could just make dummies for those ranges. But the factor variable for income is right censored. The norm is adding an extra dummy for censored/uncensored category, but this would lead to bias, according to some published papers. What is the best way to approach this problem? The dependent variable is discrete choice.