Distinguish among difference estimation, ratio estimation, mean-per-unit estimation, and stratified mean-per-unit estimation. Give one example in which each can be used.

1. Distinguish among difference estimation, ratio estimation, mean-per-unit estimation, and stratified mean-per-unit estimation. Give one example in which each can be used.
2. An essential step in difference estimation is the comparison of each computed confidence limit with tolerable misstatement. Why is this step so important, and what should the auditor do if one of the confidence limits is larger than the tolerable misstatement?