1. a variable or factor that influences both the independent and dependent variables in a study, making it difficult to determine the true relationship between them
Usage: common in statistics, research, and epidemiology
2. a person or thing that confuses or perplexes
Usage: less common; informal

Examples

• Age is a confounder in the study because it affects both smoking habits and heart disease risk.
• Researchers must control for confounders to isolate the effect of the treatment.
• Socioeconomic status is often a confounder when studying health outcomes.
• The study's results were unreliable because the researchers failed to account for confounders.
• In epidemiological research, identifying and measuring confounders is essential for valid conclusions.