What is the primary effect of confounders on experimental results?

Confounders are variables that can influence both the independent and dependent variables, potentially leading to a misleading association between them. When they are present in an experimental study, they can obscure the true nature of the relationship being investigated, causing confusion in interpreting the results. This confusion arises because the effects observed in the study may be attributable to the confounding variables rather than the primary variables of interest. In essence, confounders create a false impression or a distorted view of the relationship between the variables, which can prevent researchers from drawing accurate conclusions about causality and effect.

For example, if a study is examining the relationship between exercise and weight loss, a confounder such as diet may also play a significant role in weight changes, thereby complicating the understanding of the direct effect of exercise on weight.