As you have seen, there are many ways that bias can thwart the best laid plans of epidemiologists. Some potential sources of bias can be anticipated and addressed. However, there is always a danger that an unknown source of bias will undermine an otherwise well-planned and well-executed study.
To prepare, find an article that examines an association of interest. The article should be one published within the last 5 years in a peer-reviewed journal such as the American Journal of Epidemiology, American Journal of Public Health, Clinical Epidemiology or another journal of your choice.
Post a summary of the article. Describe the study design and comment on sources of bias that exist in that design. Give an example of how bias may have affected the findings of the study you selected. Were efforts made to minimize bias? Did the authors control for selected variables that could have been associated with the exposure and outcome of interest?
Make sure to include a link to the article in your posting.