One concept from chapter 15 in the Epstein text is the Cause and Effect in Populations. The text says that a Cause in populations is usually explained as meaning that given the cause, there's a higher probability that the effect will follow than if there were not the cause. The text used the "Smoking causes lung cancer" example for this concept but doesn't really state how smoking can cause lung cancer so they used an activity to come up with an evidence.
1. Controlled experiment: cause-to-effect.
In this experiment, people are split into two groups - one group of smokers and one group of non-smokers which is called the control group. The point of using a control group is to show that, at least statistically, the cause makes a difference.
2. Uncontrolled experiment: cause-to-effect - starts with the suspected cause and see if the effect follows.
In this experiment, there are two randomly chosen, representatives sample of the general population for other possible causes of lung cancer such as working in coal mines and a group of people who say they have never smoke. This doesn't have a controlled group.
3. Uncontrolled experiment: effect-to-cause - starts with the effect in the population and try to account for how it got there.
In this experiment, it consists of many people who have lung cancer to see if there is some common thread that occurs in (almost all) their lives. They are factored into coal mine workers, lived in high pollution areas, drank a lot and smokers.
The experiment with the controlled group would have the best evidence because if the people who smoke turns out to have a lung cancer and nothing for the non-smokers after the experiment is done, then it is clearly shows that smoking causes lung cancer.
I also liked the way that the book talked about this concept and by giving the examples of the different experiments and explaining how you can prove a cause and effect relationship was really helpful. The example of smoking causing lung cancer was also a good one to use because every day we are told that smoking causes cancer whether it be by a television ad or billboard but none of them actually tell us why or how it causes cancer. Although we do already know the answer to that, so the how is just implied.
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