To determine the effectiveness of a new pain reliever, a randomly chosen group of pain sufferers is assigned to take the new drug, and another randomly chosen group is assigned to take a placebo. The subjects taking the new drug experienced substantially more pain relief than those taking the placebo. The research team concluded that the new drug is effective in relieving pain. Which of following is correct? Since this study was confounded with a new pain reliever no conclusions should be drawn. There is a positive association between pain and the new drug. This is a matched paired design that showed pain sufferers' improvement after taking the medication. Since this study was a randomized experiment the conclusion by the research team is well justified. Since this was an observational study the conclusion by the research team is not well justified.