1. 7-9 Scatter Plots Course 2 Warm Up Problem of the Day Lesson Presentation

2. Warm Up Which of the following pairs do you think have a cause-and-effect relationship? 1. height and age 2. hand span and address 3. grade average and shoe size 4. temperature and date yes no no yes Course 2 7-9 Scatter Plots

3. Problem of the Day From the pizza shop, James walks 12 blocks south, 22 blocks east, 18 blocks north, and 30 blocks west. What is the least number of blocks that he must travel if he returns to the pizza shop? 14 Course 2 7-9 Scatter Plots

4. Learn to display and analyze data in scatter plots. Course 2 7-9 Scatter Plots

5. Vocabulary scatter plot positive correlation negative correlation no correlation Course 2 7-9 Scatter Plots

6. To find out if two sets of data may be related, you can make a scatter plot of the data values in each set. A scatter plot has two number lines, called axes —one for each set of data values. Each point on the scatter plot represents a pair of data values. These points may appear to be scattered or may cluster in the shape of a line or a curve. Course 2 7-9 Scatter Plots

7. Use the data to make a scatter plot. Describe the relationship between the data sets. Additional Example 1: Making a Scatter Plot Step 1: Determine the scale and interval for each axis. Place the number of animals endangered in the U.S. on the horizontal axis and the number of animals endangered in the rest of the world on the vertical axis. 0 20 40 60 80 300 240 180 120 60 0 Course 2 7-9 Scatter Plots Type U.S. Only Rest of World Mammals 63 251 Birds 78 175 Reptiles 14 64 Amphibians 10 8 Fishes 70 11 Clams 61 2 Number of Endangered Species

8. Additional Example 1 Continued Step 2: Plot a point for each pair of values. Course 2 7-9 Scatter Plots Type U.S. Only Rest of World Mammals 63 251 Birds 78 175 Reptiles 14 64 Amphibians 10 8 Fishes 70 11 Clams 61 2 Number of Endangered Species 0 20 40 60 80 300 240 180 120 60 0

9. Use the data to make a scatter plot. Describe the relationship between the data sets. Additional Example 1 Continued Step 3: Label the axes and give the graph a title. U.S. Rest of World Number of Endangered Species Course 2 7-9 Scatter Plots Type U.S. Only Rest of World Mammals 63 251 Birds 78 175 Reptiles 14 64 Amphibians 10 8 Fishes 70 11 Clams 61 2 Number of Endangered Species 0 20 40 60 80 300 240 180 120 60 0

10. Use the data to make a scatter plot. Describe the relationship between the data sets. Additional Example 1 Continued There appears to be no relationship between the data sets. U.S. Rest of World Number of Endangered Species Course 2 7-9 Scatter Plots Type U.S. Only Rest of World Mammals 63 251 Birds 78 175 Reptiles 14 64 Amphibians 10 8 Fishes 70 11 Clams 61 2 Number of Endangered Species 0 20 40 60 80 300 240 180 120 60 0

11. Check It Out: Example 1 Step 1: Determine the scale and interval for each axis. Place the year on the horizontal axis and the number of farm workers on the vertical axis. 1940 1960 1980 2000 10,000 8,000 6,000 4,000 2,000 Use the data to make a scatter plot. Describe the relationship between the data sets. Course 2 7-9 Scatter Plots 1940 8,995 1950 6,858 1960 4,132 1970 2,881 1980 2,818 1990 2,864 Number of farm workers in thousands Year

12. Check It Out: Example 1 Continued Step 2: Plot a point from each pair of values. Course 2 7-9 Scatter Plots 1940 8,995 1950 6,858 1960 4,132 1970 2,881 1980 2,818 1990 2,864 Number of farm workers in thousands Year 1940 1960 1980 2000 10,000 8,000 6,000 4,000 2,000

13. Check It Out: Example 1 Continued Step 3: Label the axes and give the graph a title. Year Number (in thousands) Number of Farm Workers Course 2 7-9 Scatter Plots 1940 8,995 1950 6,858 1960 4,132 1970 2,881 1980 2,818 1990 2,864 Number of farm workers in thousands Year 1940 1960 1980 2000 10,000 8,000 6,000 4,000 2,000

14. Check It Out: Example 1 Continued The number of farm workers decreased from 1940 to 1970. Year Number (in thousands) Number of Farm Workers Course 2 7-9 Scatter Plots 1940 8,995 1950 6,858 1960 4,132 1970 2,881 1980 2,818 1990 2,864 Number of farm workers in thousands Year 1940 1960 1980 2000 10,000 8,000 6,000 4,000 2,000

15. There are three ways to describe data displayed in a scatter plot. Positive Correlation The values in both data sets increase at the same time. Negative Correlation The values in one data set increase as the values in the other set decrease. No Correlation The values in both data sets show no pattern. Course 2 7-9 Scatter Plots

16. Write positive correlation , negative correlation , or no correlation to describe each relationship. Explain. Additional Example 2A: Determining Relationships Between Two Sets of Data The graph shows that as area increases, population increases. So the graph shows a positive correlation between the data sets. Course 2 7-9 Scatter Plots

17. Write positive correlation , negative correlation , or no correlation to describe each relationship. Explain. Additional Example 2B: Determining Relationships Between Two Sets of Data The number of vacation days is not related to height. So there would not be any correlation between these two variables. height and number of vacation days Course 2 7-9 Scatter Plots

18. Write positive correlation , negative correlation , or no correlation to describe each relationship. Explain. outdoor temperature and coat sales Additional Example 2C: Determining Relationships Between Two Sets of Data As the outdoor temperature increases, the number of coat sales will decrease. So there would be a negative correlation between the data sets. Course 2 7-9 Scatter Plots

19. Write positive correlation , negative correlation , or no correlation to describe each relationship. Check It Out: Example 2A The graph shows that as the year increases, number of tornados increases. So the graph shows a positive correlation between the data sets. Course 2 7-9 Scatter Plots

20. Write positive correlation , negative correlation , or no correlation to describe each relationship. Check It Out: Example 2B The graph shows that as the length of string increases, frequency decreases. So the graph shows a negative correlation between the data sets. vps = vibrations per second Course 2 7-9 Scatter Plots

21. Write positive correlation , negative correlation , or no correlation to describe each relationship. Check It Out: Example 2C There would not be any correlation between these two variables. eye color and age Course 2 7-9 Scatter Plots

22. Lesson Quiz: Part I 1. Use the data to make a scatter plot. Describe the relationship. Temperature Attendance 70 100 80 350 75 250 85 400 74 200 82 375 72 260 The graph shows a positive correlation. Course 2 7-9 Scatter Plots

23. Lesson Quiz: Part II 2. Write positive, negative, or no correlation to describe each relationship. Explain negative correlation; as age increases, attendance decreases. Course 2 7-9 Scatter Plots