MATH 1F92 Chapter Notes - Chapter 1: Framingham Heart Study, Cohort Study, Confounding
17 Sep 2016
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Distinguish between an observational study and an experiment. Example 1: researchers wanted to determine whether there is an association between cell phone and brain tumors. 791,710 middle-aged women in the uk were followed over a period of 7 years. During this time there was 1261 incidences of brain tumors. Researchers compared women who used cellphones and those who did not and found no significant difference in incidence rate of brain tumors between the two groups. 480 rats were divided randomly into three groups. Group 1 exposed to analogue; group 2 exposed to digital; group 3 exposed to no radiation: exposure was done for 4 hour a day, 5 days a week, for 2 years. Rats were treated the same except for rf radiation. After 505 days of exposure, the researchers found no statistically significant increases in any tumor type, including brain, liver, lung, or kidney compared to control group .
