Selection Bias Selection bias occurs when certain groups are overrepresented or underrepresented in the study sample. This can happen due to non-random sampling methods, loss to follow-up, or non-response from certain participants.
Information Bias Information bias results from inaccurate data collection methods. This can include recall bias, where participants do not accurately remember past events, and interviewer bias, where the interviewer’s behavior influences the responses.
Confounding Confounding occurs when an extraneous variable is associated with both the exposure and the outcome, distorting the true relationship between them. For example, age is a common confounder in studies examining the relationship between physical activity and cardiovascular disease.
