This runs counter to previous findings but there were many confounding variables.

However, these studies are not conclusive due to many confounding variables.

In this case, the endogeneity comes from an uncontrolled confounding variable.

Another issue is the way in which experimental studies deal with potential confounding variables.

However, in most studies, genes are a confounding variable.

However, it is never possible to include all possible confounding variables in an empirical analysis.

However, there are many confounding variables involved with this methodology.

This could be because of several confounding variables.

This eliminates many confounding variables that might be present in other samples, which can lead to inaccurate results.

Such confounding variables could be drug use, alcohol abuse, diet, and sexual risk taking.