18.The effect was small but it remained significant even when the findings were adjusted to take into account confounding factors like years of education and socioeconomic status.
19.In order to conduct a clinical trial properly, scientists need to be able to minimize interference from confounding variables, things that influence final measurements, without being the variable of interest.
20.The paper's authors, Daron Acemoglu of the Massachusetts Institute of Technology (MIT) and Pascual Restrepo of Boston University, are careful to exclude confounding causes as best they can.