When making a major purchase, i often spend months to learn all the issues?

A weakness of Case study research method. Case study is a detailed research strategy that focuses on a subject (the case), and all its related contextual conditions and complexities. It rises or falls with the subject because an average, or atypical case, is often not the richest source of information. There's always exceptions to everything. Since it has been proven that cigarettes kill, an 89 years old chronic smoker who has lived longer than expected would flaw the reasearch. This is obviously one of the main weakness of case study research method. If one or two subjects defy all odds that is no reason to base our assumptions/conclusions on that. It is certainly not in the researcher's best interest to gauge certain qualities, attributes, or expectations based on a particular case. Case study research method usually analyzes, scrutinizes and draws conclusions from a subject which is often inaccurate; drawing conclusions from a sample of hundreds and even thousands using one or two is often far from the main result.