One way to increase internal and external validity is by balancing, meaning we distribut the effects of an extraneous variable across treatment conditions of the experiment. We do not want to sacrifice internal validity for external validity, we must first have internal validity before we reach external validity. If you reach internal validity first, then you have a better chance at finding external validity as well. Balancing can be done as easily as assigning on half of the subjects to one room and the other half of the subjects in another room (Hansen & Myers, 2012). Balancing is a really simple technique, but it also means that you as a researcher are taking the time to make sure all your ducks are in a row before coming to your final conclusion for your results.