Does taking large amounts of vitamins protect against cancer? To study this question, researchers enrolled 29,000 Finnish men, all smokers over the age of 50. Half of the men, selected at random, took vitamin supplements, and others took a dummy pill that has no active ingredient. The researchers followed all the men for eight years. At the end of the study, men in the vitamin group were no less likely to have cancer than men in the other group. This study cast doubt on the popular idea that taking lots of vitamins can reduce the risk of cancer.
The study design looked like this:
Treatment 2 was a dummy pill. Such a dummy treatment is called a
A) double-blind technique.
B) categorical variable.
C) nonsampling error.
D) placebo.
E) comparative.

Question

Does taking large amounts of vitamins protect against cancer? To study this question, researchers enrolled 29,000 Finnish men, all smokers over the age of 50. Half of the men, selected at random, took vitamin supplements, and others took a dummy pill that has no active ingredient. The researchers followed all the men for eight years. At the end of the study, men in the vitamin group were no less likely to have cancer than men in the other group. This study cast doubt on the popular idea that taking lots of vitamins can reduce the risk of cancer.
The study design looked like this: 
Treatment 2 was a dummy pill. Such a dummy treatment is called a
A) double-blind technique. 
B) categorical variable. 
C) nonsampling error. 
D) placebo. 
E) comparative.

Quizplus · Accepted Answer

The dummy treatment used in the study is called a placebo. A placebo is a harmless pill, medicine, or procedure used as a control in clinical trials. It is designed to be identical to the real treatment or drug being tested, but it does not contain the active ingredient. This allows researchers to compare the effects of the active treatment with the effects of the placebo and determine whether the treatment actually has a significant effect. In this study, the placebo was given to the control group, while the vitamin supplements were given to the treatment group, allowing the researchers to compare the effects of the vitamins with the effects of the placebo.

Does Taking Large Amounts of Vitamins Protect Against Cancer? to Study