Problem 5 Determining Bias in a Sample

Sports You want to determine what percent of teens ages 14 to 18 watch wrestling on TV. At a high school wrestling match, you ask every third teenager whether he or she watches wrestling on TV. How might this cause bias in the results of your survey?

The sample chosen is not representative of the population. People who attend a high school wrestling match may be more likely to watch wrestling on TV.

✓ Got It?

5. You want to know how many of your classmates have cell phones. To determine this, you send every classmate an e-mail asking, “Do you own a cell phone?” How might this method of gathering data affect the results of your survey?

✓ Lesson Check

Do you know HOW?

Determine whether each sampling method is random, systematic, or stratified.

1. You survey every tenth student who enters the cafeteria.
2. You draw student ID numbers out of a hat and survey those students.
3. You survey two students at random from each class.

Do you UNDERSTAND?

4. Vocabulary Is a data set of your class's test scores qualitative or quantitative data?
5. Writing Explain why “Do you prefer delicious fruit or plain vegetables for a snack food?” is a biased survey question.
6. Compare and Contrast What is the difference between univariate data and bivariate data? Give an example of each type of data.