Monday, January 18, 2010

Why is a control variable of importance?

I need help for my quiz tomorrow! Thank you!!!!!! :)Why is a control variable of importance?
In some experiments, you need a control group to establish a baseline for performance and minimize the effect of confounding variables.





For example, someone wants to test a new drug treatment for cancer. They get a sample of patients with cancer, test tumor size, and divide them (randomly) into two groups. They give one group the new drug and the second group a placebo. Two months later they test tumor size again and find that the tumors in the treatment group have stayed the same size. Without a control group, they would probably assume that the treatment was ineffective and scrap the drug. However, checking the control group, they find that their tumors have tripled in size without treatment. Lo and behold, the drug has an effect after all!Why is a control variable of importance?
Because if you didn't have a control, then you would never know how the reaction would occur normally.

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