Read News Story 12 in the Appendix, “Working nights may increase breast cancer risk.” The story describes two separate observational studies, one by Scott Davis and co-authors and one by Francine Laden and co-authors. Both studies and an editorial describing them are included on the website, and you may need to consult them. For each of the two studies, explain whether
a. A case-control study was used. If it was, explain how the “controls” were chosen.
b. A retrospective or a prospective study was used.