The document discusses various aspects of designing effective questionnaires for research purposes. It covers determining what questions to ask and how to phrase them, the best sequence for questions, optimal questionnaire layouts, the importance of pretesting and revising questionnaires, and special considerations for designing questionnaires for global markets. The key decisions in questionnaire design involve determining the relevant questions to ask, how to phrase questions clearly and without bias, the best order of questions, and choosing a layout and format that will best serve the research objectives. Extensive pretesting and revision is important to ensure the questionnaire gathers the intended information without issues.