It&#x27;s impossible to test &quot;absolute&quot; effects of drugs, so they are always tested in relation to each-other, this makes analysis easy because the only variable that&#x27;s different is between whether participants are taking the actual drug, or a placebo. What you&#x27;re suggesting would require testing a placebo in relation to not taking anything, which would introduce a lot more variables, and would make it impossible to do double-blind testing.