In questionnaires on language contact outside a formal setting, some opt for using overlapping categories, i.e. in a question such as: 'How many hours do you spend listening to music every day' some researchers will use the following options: 0, 0-1 hours, 1-2 hours, 2-3 hours, 3-4 hours, etc. Others, on the other hand, opt for non-overlapping categories such as: 0, 0-1:00, 1:01-2:00, etc. The latter categories are endorsed by textbooks on scale creation. I cannot find literature in favour of the overlapping categories but am hoping that someone can help me find arguments in favor of such use?