<prompt> Translate the following text to EnglishKwa masuala ya kubuni, miongozo kujadili uwazi wa masuala, uhusiano wa swali tathmini kwa maombi ya utafiti wa kesi kuchaguliwa, msingi kwa ajili ya uteuzi wa utafiti wa kesi, na muda wa utafiti.  <response>: On matters of design, the guidelines discuss the clarity of issues, the relationship of the evaluation question to the case study application selected, the basis for case study selection, and the time span of the study. 