A researcher at a large pharmaceutical company wishes to study the effect of a new experimental drug on the amount of pain suffered by people who frequently experience migraines. The researcher conducts a randomized experiment, where half of the migraine sufferers who volunteer receive the experimental drug, and half receive a placebo pill. The researcher then records a pain score two hours later, and wants to formally model the pain score as a function of experimental group and other confounding variables (age, BMI, gender, and race/ethnicity).
What is the dependent variable in this model, and what are the independent variables?