Independent:The independent variable is the variable that is manipulated, i.e. changing doses in this case. Dependent: The dependent variable is the variable that is being measured or tested in an experiment. Confounding: A confounding variable, also called a confounder or confounding factor, is a third variable in a study examining a potential cause-and-effect relationship. A confounding variable is related to both the supposed cause and the supposed effect of the study Extraneous: In an experiment, an extraneous variable is any variable that you’re not investigating that can potentially affect the outcomes of your research study. If left uncontrolled, extraneous variables can lead