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In fact, the improvement was indistinguishable between those receiving the real surgery and those receiving the fake surgery!Source: “The Placebo Prescription,” NY Times Magazine, 1/9/00.
Statistics: Unlocking the Power of DataLock5Placebo EffectOften, people will experience the effect they think they should be experiencing, even if they aren’t actually receiving the treatment Example: EurotripThis is known as the placebo effectOne study estimated that 75% of the effectiveness of anti-depressant medication is due to the placebo effect For more information on the placebo effect (it’s pretty amazing!) read The Placebo Prescription
Statistics: Unlocking the Power of DataLock5Study on PlacebosBlue pills are better than yellow pillsRed pills are better than blue pills2 pills are better than 1 pill4 pills are better than 2 pillsAnd shots are the best of all!
Statistics: Unlocking the Power of DataLock5Placebo and BlindingControl groups should be given a placebo, a fake treatment that resembles the active treatment as much as possibleUsing a placebo is only helpful if participants do not know whether they are getting the placebo or the active treatmentIf possible, randomized experiments should be double-blinded: neither the participants or the researchers involved should know which treatment the patients are actually getting
Statistics: Unlocking the Power of DataLock5Green Tea and Prostate CancerA study was conducted on 60 men with PIN lesions, some of which turn into prostate cancerHalf of these men were randomized to take 600 mg of green tea extract daily, while the other half were given a placebo pillThe study was double-blind, neither the participants nor the doctors knew who was actually receiving green teaAfter one year, only 1 person taking green tea had gotten cancer, while 9 taking the placebo had gotten cancer
Statistics: Unlocking the Power of DataLock5Green Tea and Prostate CancerA difference this large is unlikely to happen just by random chance. Can we conclude that green tea really does help prevent prostate cancer?(a) Yes(b) NoGood randomized experiments allow conclusions about causality.
Statistics: Unlocking the Power of DataLock5Why not always randomize?Randomized experiments are ideal, but sometimes not ethical or possibleOften, you have to do the best you can with data from observational studiesExample: research for the Supreme Court case as to whether preferences for minorities in university admissions helps or hurts the minority students
Statistics: Unlocking the Power of DataLock5Was the sample randomly selected?Possible to generalize to the populationYesShould not generalize to the populationNoWas the explanatory variable randomly assigned?