12.1 – Designing a Survey

1. 12.1 – Designing a Survey

2. Sample – a portion of a larger group, typically called the population.

3. Sample – a portion of a larger group, typically called the population. Types of Data Collection

4. Sample – a portion of a larger group, typically called the population. Types of Data Collection • Survey – data are from responses given by a sample and used to make a general conclusion about the population.

5. Sample – a portion of a larger group, typically called the population. Types of Data Collection • Survey – data are from responses given by a sample and used to make a general conclusion about the population. • Observational Study – data are recorded after just observing the sample and used to compare reactions and draw a conclusion about responses of the population.

6. Sample – a portion of a larger group, typically called the population. Types of Data Collection • Survey – data are from responses given by a sample and used to make a general conclusion about the population. • Observational Study – data are recorded after just observing the sample and used to compare reactions and draw a conclusion about responses of the population. • Experiment – data are recorded after changing the sample and used to make general conclusions about what will happen during an event.

7. Ex. 1 A local charity is interested in finding out whether people are likely to give money to charity. They distributed 1000 questionnaires to people living in the neighborhood.

8. Ex. 1 A local charity is interested in finding out whether people are likely to give money to charity. They distributed 1000 questionnaires to people living in the neighborhood. • Identify the sample and determine the population from which it was selected.

9. Ex. 1 A local charity is interested in finding out whether people are likely to give money to charity. They distributed 1000 questionnaires to people living in the neighborhood. • Identify the sample and determine the population from which it was selected. The sample is the 1000 people who received the questionnaires. The population is all the people in the neighborhood.

10. Ex. 1 A local charity is interested in finding out whether people are likely to give money to charity. They distributed 1000 questionnaires to people living in the neighborhood. • Identify the sample and determine the population from which it was selected. The sample is the 1000 people who received the questionnaires. The population is all the people in the neighborhood. • Classify the type of data collection used by this charity.

11. Ex. 1 A local charity is interested in finding out whether people are likely to give money to charity. They distributed 1000 questionnaires to people living in the neighborhood. • Identify the sample and determine the population from which it was selected. The sample is the 1000 people who received the questionnaires. The population is all the people in the neighborhood. • Classify the type of data collection used by this charity. This is a survey b/c the data are from responses given by people in the sample.

12. Ex. 2 Identify each sample as biased or unbiased. Explain your reasoning.

13. Ex. 2 Identify each sample as biased or unbiased. Explain your reasoning. • Every fifth person coming into a grocery store is asked to name a favorite radio station.

14. Ex. 2 Identify each sample as biased or unbiased. Explain your reasoning. • Every fifth person coming into a grocery store is asked to name a favorite radio station. Unbiased b/c the sample is a random selection of people.

15. Ex. 2 Identify each sample as biased or unbiased. Explain your reasoning. • Every fifth person coming into a grocery store is asked to name a favorite radio station. Unbiased b/c the sample is a random selection of people. • Every fifth person at the Country Music Showcase is asked to name their favorite radio station.

16. Ex. 2 Identify each sample as biased or unbiased. Explain your reasoning. • Every fifth person coming into a grocery store is asked to name a favorite radio station. Unbiased b/c the sample is a random selection of people. • Every fifth person at the Country Music Showcase is asked to name their favorite radio station. Biased b/c they are more likely to select a country music station.

17. Types of Random Samples

18. Types of Random Samples • Simple – a sample that is equally likely to be chosen as any other sample from the population.

19. Types of Random Samples • Simple – a sample that is equally likely to be chosen as any other sample from the population. • Stratified – the population is first divided in similar, non-overlapping groups, then a random sample is selected from each group.

20. Types of Random Samples • Simple – a sample that is equally likely to be chosen as any other sample from the population. • Stratified – the population is first divided in similar, non-overlapping groups, then a random sample is selected from each group. • Systematic – a sample in which the items in the sample are selected according to a specified time or item interval.

21. Ex. 3 Animals in a zoo are divided by continents. Then two animals were selected at random from each group to have their blood tested.

22. Ex. 3 Animals in a zoo are divided by continents. Then two animals were selected at random from each group to have their blood tested. • Identify the sample and suggest a population from which it was selected.

23. Ex. 3 Animals in a zoo are divided by continents. Then two animals were selected at random from each group to have their blood tested. • Identify the sample and suggest a population from which it was selected. The sample is the two animals selected from each continent. The population is the animals at the zoo.

24. Ex. 3 Animals in a zoo are divided by continents. Then two animals were selected at random from each group to have their blood tested. • Identify the sample and suggest a population from which it was selected. The sample is the two animals selected from each continent. The population is the animals at the zoo. • Classify the sample as simple, stratified, or systematic. Explain your reasoning.

25. Ex. 3 Animals in a zoo are divided by continents. Then two animals were selected at random from each group to have their blood tested. • Identify the sample and suggest a population from which it was selected. The sample is the two animals selected from each continent. The population is the animals at the zoo. • Classify the sample as simple, stratified, or systematic. Explain your reasoning. This is stratified b/c the animals are divided up into categories before there is a random selection.