Questionnaire designers have available to them a variety of pretest techniques, including debriefing, expert review, behavior coding and cognitive testing. Although it is nearly univefrsal for survey textbooks and questionnaire designers to advocate pretesting questionnaires, few straightforward guidelines exist to determine a sample size which will maximize the efficiency of a pretest. Experts' recommendations about the appropriate size of questionnaire pretests cover a substantial range. For example, according to Sudman (1983), "A pilot test of 20 - 50 cases is usually sufficient to discover the major flaws in a questionniare before they damage the main study" (p.181).