Question

Case 3: Recently, an association that represented police in New Jersey complained that the incidence of cancer was unusually high among police officers who used radar guns in tracking the speed of drivers. The association brought suit against the state, claiming that those officers who used these radar guns had an incidence of cancer 18 percent higher than a comparable group of government workers from the state park service who were randomly selected for comparison purposes. The comparison sample and the police officers were matched on educational level, age, gender, and years of service. The sample was large: 283 police officers and 231 park workers.

Was the case justified? Why or why not? (Be sure to support your answer with reference to the strengths and weaknesses of the design, and consider possible confounds.)

What kind of study is this? What are the problems associated with this kind of study?

How would you improve the study?

Answer 1

The study was meant to asses whether using radar guns had any association with cancer. In this study the police officers handling the radar guns were compared with a sample of government workers from state park service. These two samples are totally different, which causes many other confounding variables to arise, as the sample itself is different. So, the difference we see may not be related to radar guns, but may be related to other factors. Therefore, the case is not justified, as the incidence of cancer cannot be attributed directly to the use of radar guns.

Our aim is be only to measure effect of radar guns on the incidence of cancer among police officers. For this, both the groups should consists of police officers, only expect one group handles radar guns and the other does not. Both the groups which consists police officers, are matched on educational level, age gender, years of service etc. But, one group should be of police officers who use radar guns, and the other who doesn't. These two groups should be now measured on the incidence of cancer. The difference of incidence in cancer rates between groups may suggest that radar guns use is related to cancer.