thelosthippie wrote:
In 1990, nearly 80% of people in the United States reported that they knew someone who had been diagnosed with cancer. In 2010, that percentage remained unchanged yet cancer incidence rates in the population increased by over 40% from 1990 to 2010.
Which of the following, if true, would best explain how the percentage of people who knew someone with cancer could have remained unchanged despite the dramatic increase in the incidence of cancer?
A. Improved treatment options dramatically reduced cancer mortality rates from 1990 to 2010.
B. From 1990 to 2010, most new cases of cancer occurred in densely populated urban centers with previously high cancer rates.
C. Many of the new cancer cases from 1990 to 2010 occurred in geographically isolated regions where little or no cancer had been present before.
D. From 1990 to 2010, some of the new cancer cases occurred in people who had previously been diagnosed with another form of cancer.
E. Because of dramatic technological improvements in diagnostic tools from 1990 to 2010, cancer was more likely to be diagnosed in 2010 than in 1990.
Look at the given information:
1990 -
Say population is 100. Say there are 10 networks of 10 people each.
80 people knew someone diagnosed with cancer.
8 people from different networks diagnosed with cancer. So of the 10 networks, 8 networks came to know.
2010 -
Say population is 200. Say there are 20 networks of 10 people each.
160 people knew someone diagnosed with cancer.
So we would expect that 16 people from different networks were diagnosed with cancer. But we are given that actually 22 people were diagnosed.
Now this is a paradox, right? The incidence rate increased from say 8% of the population to 11% of the population. But still only 80% population knew someone who had been diagnosed with it.
How can we explain it? In my pre-thinking, I thought that perhaps the people diagnosed were from the same network. So perhaps it has a major genetic component (so in the same family) or environmental so people living nearby got affected (people living nearby would be expected to be in the same network) etc.
A. Improved treatment options dramatically reduced cancer mortality rates from 1990 to 2010.
Mortality is irrelevant in this argument. We are talking about "people diagnosed". Whether they were able to successfully overcome the disease or not does not affect any of our numbers. (Feeling terrible while writing this but we need to stick to the scope of our argument.)
B. From 1990 to 2010, most new cases of cancer occurred in densely populated urban centers with previously high cancer rates.
Correct. So areas that already had high incidence of the disease got more new cases. People living in the same areas are expected to be in the same network. So this is another way of saying that people from the same network got affected.
C. Many of the new cancer cases from 1990 to 2010 occurred in geographically isolated regions where little or no cancer had been present before.
This says that people from other networks got impacted. Then the number of 80% would have increased. More networks would have known people diagnosed.
D. From 1990 to 2010, some of the new cancer cases occurred in people who had previously been diagnosed with another form of cancer.
We know that incidence rates have increased. This means, in 2010, 40% more people have been diagnosed. Whether some of them were diagnosed previously too, doesn't matter.
E. Because of dramatic technological improvements in diagnostic tools from 1990 to 2010, cancer was more likely to be diagnosed in 2010 than in 1990.
This could explain why incidence of cancer increased by 40% but it doesn't explain why still only 80% population knows someone who is diagnosed.
Answer (B)