3. [9pts] The Canadian National Breast Cancer Study was a randomized controlled

Question

3. [9pts] The Canadian National Breast Cancer Study was a randomized controlled experiment on mammography, that is, x-ray screening for breast cancer. The study found that screening was beneficial, especially for older women. Benefits were measured by comparing death rates in the treatment and control groups. One doctor argued that the randomization was not done properly: instead of following instructions, nurses assigned high-risk women to the screening group. Would this bias the study? If there is bias, does the bias cause the screening to appear less effective than it really is? Explain your answers completely.

Explanation / Answer

Yes, This will bias the study.

A randomized controlled experiment is a type of experiment which aims to reduce bias when testing a new treatment. The people participating in the trial are randomly assign to either the group receiving the treatment under investigation or to a group receiving standard treatment (or placebo treatment) as the control. Randomization minimises selection bias and the different comparison groups allow the researchers to determine any effects of the treatment when compared with the no treatment (control) group, while other variables are kept constant.

Since trials are randomly allocated to either the group receiving the treatment under investigation or to a group receiving standard treatment (or placebo treatment) as the control.In our case nurses assigned high-risk women to the screening group hence there is possibility that test will tent to a group with high-risk women more than the other group and this will create bias in study. hence this bias will cause the screening to appear less effective than it really is.

Hope this is clear.

Cheers.

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