1. Algebra I Chapter 12.1 Samples and Studies

2. Sampling
Population: The entire group Sample: The group being studied

3. Systematic Sampling
Members are selected according to a specified pattern. Example:

4. Self-Selected Sample
Members volunteer to participate in the study. Example:

5. Convenience Sample
Members are selected because they are easy to reach. Example:

6. Stratified Sample
Members of a population are divided into distinct subgroups. Then, members are selected at random from each group. Example:

7. Turn and Talk
Which of these methods of sampling seems the best to you? Why? Which of these methods seems problematic? Why?

8. Example 1:
Identify the sample and the population. Then determine if the sample is random, self-selected, convenience, or stratified. Students at AHS are listed alphabetically. Every fourth student on the list is selected to participate in a study on lunch food.

9. Example 2:
Identify the sample and the population. Then determine if the sample is random, self-selected, convenience, or stratified. Animals at a zoo are divided into groups based on their species. Random animals are then selected from each group to have their blood tested.

10. Example 3:
Identify the sample and the population. Then determine if the sample is random, self-selected, convenience, or stratified. A manager at a supermarket polls the people who come into his store on their eating habits.

11. Bias
An error that results in the misrepresentation of a population.

12. Example 1:
Determine if each sample is biased or unbiased. Explain your decisions. A student polls members of student council to learn more about levels of student involvement at AHS.

13. Example 2:
Determine if each sample is biased or unbiased. Explain your decisions. A blogger asks people at a country music festival what their favorite radio station is.

14. Example 3:
Determine if each sample is biased or unbiased. Explain your decisions. A journalist surveys members of a Young Democrats group to learn more about the political opinions of young voters.

15. Types of Studies Name Description Example Census Survey
Observational Study
Experiment

16. Example 1
Determine if each scenario is a census, survey, observational study, or experiment. A company shows five different commercials to students, and records their reactions.

17. Example 2
Determine if each scenario is a census, survey, observational study, or experiment. A school polls their students about the types of food they would like to see in their cafeteria. Every third student receives a questionnaire.

18. Example 3
Determine if each scenario is a census, survey, observational study, or experiment. All American citizens respond to a questionnaire regarding household income.

19. Example 4
Determine if each scenario is a census, survey, observational study, or experiment. A research group wants to learn how rats react to different diets.

20. Questioning
Survey questions must not be biased. Errors in questioning are made when questions: - are confusing - encourage answering in a certain way - cause a strong reaction - address more than one issue at a time

21. Example 1
Determine if each question is biased or unbiased. Explain your decisions. Is your favorite flavor of ice cream vanilla or delicious chocolate?

22. Example 2
Determine if each question is biased or unbiased. Explain your decisions. Don’t you think that Obama is a great president?

23. Example 3
Determine if each question is biased or unbiased. Explain your decisions. What do you eat for breakfast?

24. Example 4
Determine if each question is biased or unbiased. Explain your decisions. Do you like animals, and would you rather have a dog or a cat?