Representative sample

1. Could we use a random sample to discover whether or not peoples’ education level impacts their likelihood to vote in a presidential election?

2. In this lesson you will learn how to make inferences about a population with an unknown characteristicby analyzing random samples.

3. Random sampling method Representative sample Valid inference

4. Blue is the preferred color. Some students make an inference or generalization even if the data doesn’t show a significant pattern.

5. Unknown characteristic Trout ? Whitefish ? ? ? Walleye

6. Random sample: 300 fish ? 125 Trout Inferences about population ? ? 130 Whitefish 45 Walleye

7. Making inferences More/less than Twice as many as Tends to increase/decrease

8. Inferences There are more trout and whitefish than walleye in the lake Random Sample 125 Trout Whitefish is the most common fish 130 Whitefish There are about 1/3 as many walleye as trout or whitefish 45 Walleye

9. In this lesson you have learned how to make inferences about a population with an unknown characteristicby analyzing random samples.

10. Data: Survey of a random sample of Americans What inferences can be made from the graph?

11. Extension Activities Which is the most valid inference? Black is the least preferred color. More students prefer blue than prefer black and green combined. Blue and green are the preferred colors. Pink is preferred to black.

12. Extension Activities Create a survey question and five possible responses. Collect data from a sample of your class in a table like the one below. Make two inferences about your entire grade by analyzing the data from your sample.

13. Explain why Kyle’s inference may be invalid. Kyle: People with graduate degrees vote more often than people with only college degrees.

14. To predict middle school students’ ice cream preferences, a random sample of 1,300 students was surveyed about their preferences between ice cream flavors. 1) Make two inferences about the population.

15. 2) Which is the most valid inference from this sample data? Strawberry is the least preferred flavor. b) More students prefer cookie dough ice cream than prefer chocolate and vanilla combined. c) Cookie dough and mint chocolate chip are the preferred ice cream flavors. d) Chocolate ice cream is preferred to strawberry