1. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Example 1
Classify a sampling method
Study Time A high school is conducting a survey to determine the average number of hours that their students spend doing homework each week. At the school, only the members of the sophomore class are chosen to complete the survey. Identify the population and classify the sampling method.
Solution
The population is ___________________________.
all of the school’s students
Because a rule (sophomore class only) is used to select members of the population, the sample is a ____________ sample.
systematic

2. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Example 2
Identify a potential biased sample
Is the sampling method used in Example 1 likely to result in a biased sample?
Solution
Students in other grades may have different study habits, so the method ____________ in a biased sample.
may result

3. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Example 3
Identify potentially biased questions
Tell whether the question is potentially biased. Explain your answer. If the question is potentially biased, rewrite it so that it is not,
Do you still support the schools basketball team, even though the team is having its worst season in 5 years?
Solution
The question is biased because _______________ _________________________________________________________________.
it suggests that
people should not support a basketball team that is doing poorly
An unbiased question is, “__________________ ___________________________”
Do you support
the school basketball team?

4. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Example 3
Identify potentially biased questions
Tell whether the question is potentially biased. Explain your answer. If the question is potentially biased, rewrite it so that it is not,
Don’t you think that dogs are better pets than cats?
Solution
The question is biased because _______________ ____________________________.
it suggests that
dogs are better pets than cats
An unbiased question is, “__________________ ________________________”
Do you think dogs
or cats make better pets?

5. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Checkpoint. Complete the following exercises.
In Example 1, suppose the school asks students to volunteer to take the survey. Classify the sampling method.
Self-selected sample

6. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Checkpoint. Complete the following exercises.
An amusement park owner wants to evaluate the customer service given by the park’s ride operators. On day, every 10th customer leaving the park was asked, “Don’t you think our friendly, well-trained ride operators provided excellent customer service today?”
Is the sampling method likely to result in a biased sample? Explain.
No.
In this systematic sample, the rule to choose survey participants is not biased.

7. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Checkpoint. Complete the following exercises.
An amusement park owner wants to evaluate the customer service given by the park’s ride operators. On day, every 10th customer leaving the park was asked, “Don’t you think our friendly, well-trained ride operators provided excellent customer service today?”
Is the question potentially biased? Explain your answer. If the question is potentially biased, rewrite it so that it is not.
This question is biased because it suggests that the ride operators did provide excellent customer service.
An unbiased question is “Do you think that our ride operators provided excellent customer service?”

8. Analyze Surveys and Samples
6.6
Analyze Surveys and Samples
Pg. 380, 6.6 #1-11