A 5-year prospectA 5-year prospective cohort study has just been completed. The study was designed to assess the association between supplemental vitamin A exposure and mortality and morbidity from measles. The RR for incidence of measles was 0.75, and the RR for measles mortality was 0.5. Which statement is correct?
1- A cohort study is not an appropriate study design in this case because the association between one exposure and two different outcomes is being considered.
2- One of the problems that this study may have faced is individuals lost to follow-up during the 5-year period.
3- A cohort study was not a good design to study this association because measles is a very common disease.
4- None of the above