Additional study designs included in this lesson were cross-sectional, ecological, and experimental. Along with case-control and cohort study designs, these give a good overview of typical study designs used for epidemiologic research. There are also other study designs as well that are not covered in this class, including specific types of experimental study designs. The most important thing to keep in mind is the research question. Only once the investigators are clear about the research question, can the team decide the best study design to use. The study design must fit and be able to answer the research question and not the other way around.  

Cross-sectional studies take a snapshot of a population and are often used for public health planning. The National Health Interview Survey is an example of a cross-sectional survey that has been done over the years to monitor the health of the US population. Although it is done yearly, the same individuals are not included, so it is different from a cohort study. Ecological studies include at least one study variable measured at the group level. These can be very useful for the initial investigation of causal hypotheses, but it is important to be aware and cautious of the possibility of an ecological fallacy. Finally, experimental studies are in contrast to observational studies in that the investigators assign participants to certain study conditions. Both observational and experimental studies are important for the advancement of public health, and it is important to consider the pros and cons of each when deciding how best to study the research/policy/health question of interest.