Individual based studies examine how exposure and disease affect an individual person on a case by case nature without including the community as a whole. The aim is to determine differences within individuals of the same population. An example from the epiville module would be to look at Porks-a-lot pig farm employees and see if they have a higher risk of developing Susser Syndromecompared to the rest of the population of Epiville. Population based studies look at specific populations of people and how exposures and disease are impacting that specific population. This is represented in the ecological study hypotheses because it is determining Susser Syndrome cases based on incidence of being serviced by the Rothman Reservoir or the Greenland Reservoir population. The units for ecological studies are “populations or groups of populations rather than individuals.” Our hypothesis is that Rothman Reservoir will have a high incidence of Susser Syndrome cases compared to the Greenland Reservoir population. This comparison involves a population being serviced by Rothman and a population being serviced by Greenland. The exposure/disease relationship that I am interested in studying is the correlation between HPV and the development of cervical cancer. For an ecological study, I would look at publically available data on HPV and compare them to compare them to incidence of cervical cancer across regions of the United States. My hypothesis would state that there is a mutual relationship between high prevalence of HPV and the incidence of cervical cancer. For an individual-level study, I could do a case-control study and get participants to join the study from the local hospital. I would enroll patients that had cervical cancer and patients that did not have cervical cancer. From there, I would compare the women that had the disease to the women that did not have the disease. My hypothesis would be that the women from the group that had cervical cancer had possible risk factors (such as HPV) that resulted in the development of cervical cancer. I would be able to look at the many different exposures of the two groups and see what happened in the past. An ecological fallacy is when we try to use statistics/characteristics that we have collected on a population level and try to apply it on an individual level. An inference is made about individuals based on the data that was obtained from the population. From our ecological study we determined there was an increase in Susser Syndrome cases in the population that is serviced by Rothman Reservoir. If we then went on to say that individuals that were drinking the water from the Rothman Reservoir has double the chance of developing Susser Syndrome than theindividuals that were drinking the water from the Greenland Reservoir, this would be an example of an ecological fallacy. We are making an inference about the individual based off the information of that we obtained from the population, even though it has not yet been proven. Another example is that it has been documented that there has been a large increase in autism in the group on children that receive vaccinations since 1998 (lecture notes: Cross-sectional studies). It would be an ecological fallacy if we were to say that vaccine use causes autism, since on the individual level it has been proven that this is not the case.