In fact the improvement was indistinguishable between

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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 Data Lock 5 Placebo Effect Often, people will experience the effect they think they should be experiencing, even if they aren’t actually receiving the treatment Example: Eurotrip This is known as the placebo effect One 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 Data Lock 5 Study on Placebos Blue pills are better than yellow pills Red pills are better than blue pills 2 pills are better than 1 pill 4 pills are better than 2 pills And shots are the best of all!
Statistics: Unlocking the Power of Data Lock 5 Placebo and Blinding Control groups should be given a placebo , a fake treatment that resembles the active treatment as much as possible Using a placebo is only helpful if participants do not know whether they are getting the placebo or the active treatment If 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 Data Lock 5 Green Tea and Prostate Cancer A study was conducted on 60 men with PIN lesions, some of which turn into prostate cancer Half of these men were randomized to take 600 mg of green tea extract daily, while the other half were given a placebo pill The study was double-blind, neither the participants nor the doctors knew who was actually receiving green tea After one year, only 1 person taking green tea had gotten cancer, while 9 taking the placebo had gotten cancer
Statistics: Unlocking the Power of Data Lock 5 Green Tea and Prostate Cancer A 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) No Good randomized experiments allow conclusions about causality.
Statistics: Unlocking the Power of Data Lock 5 Why not always randomize? Randomized experiments are ideal, but sometimes not ethical or possible Often, you have to do the best you can with data from observational studies Example: 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 Data Lock 5 Was the sample randomly selected? Possible to generalize to the population Yes Should not generalize to the population No Was the explanatory variable randomly assigned?

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