The goal of mixed mode is to combine data from different sources. This assumes that data can be validly combined and that there is equivalence of measurement. Data from different modes may be different because the modes themselves lead to different response processes, or because different questions are employed in different modes (either by tradition or due to mode specific optimization of the questionnaire). When accommoda ting for the restricted channel capacity of telephone surveys, designers often use unfolding in questions with longer lists of response categories, while in modes that use visual presentation the full list of response categories is presented. Another question design feature often employed over the telephone is end-labeling of response categories in stead of full labeling...