A Washington Post article reported on a study about alcohol consumption and cancer in women. Since 1996, a team of British researchers has been gathering detailed information from 1.28 million women aged 50 to 64. The researchers recorded how much alcohol the women reported consuming when they volunteered for the study and again three years later. The researchers then examined whether there was any link with the 68775 cancers the women developed over an average of the next seven years. They found that even among women who consumed as little as 10 grams of alcohol a day on average (the equivalent of about one drink), the risk for cancer of the breast, liver, and rectum was elevated.

Required:
a. Is this an experiment? Explain your answer.
b. We would prefer a sample survey to using women who volunteer for a study. What population does it appear that the researchers were interested in?
c. What variables did they measure?

Why not? Because the participants aren't divided into two groups of control group vs treatment group. This is an observational survey in which the researchers are asking each participant about the alcohol consumption level (independent variable) and how it may be tied to the risk of cancer (dependent variable).

======================================================

Part B

The population appears to focus on all women between the ages of 50 and 64.

The sample of the 1.28 million women is not the population, but rather, it ideally tries to approximate the population the best it can.

======================================================

Part C

The independent variable is the alcohol consumption rate, i.e. how much beer/wine/etc was consumed. Think of it like the variable x as the input of a function.

The dependent variable is the cancer rate. It's similar to the y output of a function. The dependent variable depends on the independent variable; hence the name. The study is trying to see if altering the amount of alcohol somehow alters the rate of cancer.

Keep in mind that cancer is still a very ongoing subject of research. Unfortunately we still have a lot to learn about it. Despite this, it's highly unlikely that alcohol is the direct cause of cancer. So instead, we consider that these variables are correlated in some way even if a link is found/proven. Other factors need to be considered such as

fitness level
diet, other than the alcohol consumption
environmental factors other than the alcohol consumption (eg: does the woman live nearby an industrial plant perhaps?)
genetics
possibly other factors I haven't thought of to list here