What does the formula for optimum allocation tell us about which strata should be more heavily sampled? 8. a) 366 b) what are the biggest advantages of cluster sampling? c) d) のり e) f) Give as many reasons as you can think of for why you might want to stratify. Under what conditions does stratified random sampling produce the greatest gains in precision over SRS? What criteria should you keep in mind when choosing strata? When would you consider using ratio estimation in a SRS?