In statistics, a confounding factor (also confounding variable, lurking variable, confound, or confounder) is an extraneous variable in a statistical model that correlates (positively or negatively) with both the dependent variable and the independent variable.
A confounding factor occurs when the effect or association between an exposure and outcome is distorted by the presence of another variable (confounding variable), resulting in a “mixing of effects
Recommendations to the authors include: control several confounding factors during design and implementation of the study, i.e., by performing the sample size calculation, adequate allocation, having a control group, and using masking procedures.