Assignment
Part 1
As in the Module Discussion, we will consider the town of Springfield, where there are 100,000 adults. Consider a different genetic disease, which affects only 0.1% of the U.S. population. The test for this disease is also 98% accurate. All the adults in Springfield were also tested for this disease.
1. Use a table to organize your results, like those in the text (e.g., Table 3.7 on page 175) or like one you or a fellow discussion group member may have employed in the discussion. Include this table in your write-up. While referring to this table, answer the following questions:
1. How many of the residents of Springfield are likely to have the disease?
2. How many of the people who actually have the disease get a positive test result?
3. How many of the people who do not have the disease get a positive test result?
4. Of the people who get a positive test result, how many of them have the disease? Convert this to a percentage: What percent of people who get a positive result actually have the disease?
2. Compare your results with the problem you solved in the discussion activity (M8D1). Specifically, focus on the percent of people who get a positive result that actually have the disease. Remember that both genetic tests were 98% accurate. Why were the percentages so different? State a conclusion about how the rarity of a disease affects testing results.
Part 2
Consider a particular genetic disease affects 3% of adults in the U.S. population. Fortunately, there is a genetic test for the gene that causes the disease. The test is 98% accurate; that is, 98% of the people who take the test get the correct result (and 2% of people tested get the wrong result).
In Springfield, there are 100,000 adults, and they all get tested for the disease.
1. How many of the residents of Springfield are likely to have the disease?
2. How many of the people who actually have the disease get a positive test result?
3. How many of the people who do not have the disease get a positive test result?
4. Of the people who get a positive test result, how many of them have the disease? Convert this to a percentage: What percent of people who get a positive result actually have the disease?
5. What does this percentage tell you about the test?