Questions from Smoking Video

1. What are the advantages and disadvantages of a retrospective study?
2. What are the advantages and disadvantages of a prospective study?
3. How did the animal study help further the case for a causality relationship between smoking and lung cancer?
4. In the video, they talked about a hypothetical experiment where half the babies in the group are given cigarettes and the other half are prohibited from smoking, and the cancer rates of the two groups are compared in 50 years. Ethical issues aside, why would this give a better indication of whether or not smoking causes cancer than either the retrospective or prospective studies?