1. Samples and Populations
Making Comparisons and Predictions

2. Choosing a Sample from a Population
Investigation 2
Choosing a Sample from a Population

3. Homework
Pg 45 due 5/3 A 1,5,10,15,16,39 B 2,6,11,15,16,41 IXL L8 and L10 Percentages due 5/3

4. Vocab
Sample smaller part of the population Sampling Plan strategy for choosing a sample from a population Five-Number Summary Used for a box and whisker plot, lowest number, highest number, median, median lf lower data, median of high data Sampling Distributions showing how the means vary across samples

5. Vocab
Representative Samples sample should have characteristics similar to the original population Convenience Sampling choosing a sample based on the availability of respondents, people who are easy to locate Systematic Sampling using a methodological technique, choosing the 5th name from an alphabetical list of students in each grade level Voluntary-response Sampling asking people to choose to participate, hand out surveys to all students and ask them to return completed forms to a box in the school office Random Sampling giving every member an equally likely chance of being selected, choose student names or numbers by writing them all on slips of paper, mixing them in a bowl and selecting slips of paper

6. Invest 2.1 Asking About Honesty Using a Sample to Draw a Conclusion
What is a population? What is a sample? What is a sampling plan?

7. Notes
Remember relative frequency is a percent Table of the data questions and relative frequency Make a bar graph of data

8. Example pg 35 What is the population for Honesty Survey?
the population of the united states
2. What is the sample?
readers of magazine who log and do survey
3. How was the sample chosen from the population?
ask people to answer the survey

9. Suppose 5280 people completed the survey.
for the first question 3960 people said they would try to return the wallet, 792 said they would return the wallet but keep the money, and 528 said they would keep the wallet and the money. What is the relative frequency of each response?
75%, 15%, 10%
Second question 4752 said they would tell the cashier about the error. What is the relative frequency of respondents who said they would tell the cashier about the error?
90%

10. 3. Make a table and graph that shows the relative frequencies of “honest” and “dishonest answers

11. Homework
You should be able to do the following problems 1-4 and 39

12. Invest 2.2 Selecting A Sample Different Kinds of Samples
How could you select a sample of your school population to survey?

13. Notes
Using new terms of types of samples to determine examples of each Being about to determine between types and come up with other examples

14. Example pg 37
What are advantages and disadvantages of each sampling plan?
Which plan do you think will collect the most accurate data to represent students in the whole school?
Why is group 1 a convenience plan?
Why is group 2 a systematic plan?
Why is group 3 a voluntary-response plan?
Why is group 4 a random sample?

15. Jahmal comes up with a new plan
Jahmal comes up with a new plan. He thinks each teacher should select one boy and one girl and ask them the survey questions. There are four teachers for each grade, 6-8, so they would end up with a sample of 24 students.
a. What type of sampling plan is this?
closest is a random sample
b. Will it give a representative sample?
It does represent the student body, assuming the teachers choose the students randomly

16. Homework
You should be able to do the following problems 5-9 and 40

17. Invest 2.3 Choosing Random Samples Comparing Samples Using Center and Spread
How could you use statistics of a random sample of data to make predictions about an entire population?

18. Notes
More practice making line plots and box and whisker plots Being able to compare sample groups and the data you see

19. Example pg 40
1. Pic a sample of 30 students from data in the book 2. Make a line plot showing number of movies watched 3. Locate the man, describe the shape and find MAD 4. Make a box and whisker plot 5. Compare with other groups that used a different sample

20. Homework
You should be able to do the following problems 10-14

21. Invest 2.4 Growing Samples What Size Sample to use
Can you make good statistical estimates with less work by selecting smaller samples? How does sample size relate to the accuracy of statistical estimates?

22. Notes
Picking a sample Compare class data through graphs and tables

23. Example pg 43
Pic a sample of 5 students and a sample of 10 students, use sample of 30 from previous problem
Find mean, median, IQR and MAD for hours slept and movies watched
Record the other class groups data in a table, next page

24. Larger sample space the better the estimate of the mean5
Mean
Medain
IQR
MAD
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 8
Group 9 30
Mean
Medain
IQR
MAD
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 8
Group 9 10
Mean
Medain
IQR
MAD
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 8
Group 9
Make a line plot and a box and whisker plot for each table of the means from each table
What do you notice?
Larger sample space the better the estimate of the mean
How do you think the median, IQR and MAD will look

25. Homework
You should be able to do the following problems and 41

26. Essential Questions
Investigation 2.1 What is a population? What is a sample? What is a sampling plan? Investigation 2.2 How could you select a sample of your school population to survey? Investigation 2.3 How could you use statistics of a random sample of data to make predictions about an entire population? Investigation 2.4 Can you make good statistical estimates with less work by selecting smaller samples? How does sample size relate to the accuracy of statistical estimates?