Scatter Plots Below is a sample scatter plot
Scatter Plots Below is a sample scatter plot, can you tell me what they are designed to show.
ANSWER • Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot data points. • Scatter plots are most often used to show correlations or relationships among data.
Common Core #25 Make a scatter plot and interpret them
Scatter Plots Type #1 • Positive correlations occur when two variables or values move in the same direction. ØAs the number of hours that you study increases your overall class grade increases
Scatter Plots – Positive Correlation Study Time Class Grade 0 55 0. 5 61 1 67 1. 5 73 2 81 2. 5 89 3 91 3. 5 93 4 95 4. 5 97 Make a prediction for a study time of 5 hours.
Scatter Plot Type #2 • Negative Correlations occur when variables move in opposite directions As the number of days per month that you exercise increases your actual weight decreases
Scatter Plots – Negative Correlation Make a prediction for 12 days worked out. Work out time Weight 0 200 0. 5 205 1 190 1. 5 195 2 180 2. 5 190 3 170 3. 5 177 4 160 4. 5 170 5 150 5. 5 168 6 140 6. 5 150 7 130 7. 5 170 8 120 8. 5 130 9 110 9. 5 115 10 10. 5 120 11 90 11. 5 90
Scatter Plots #3 • No correlation exists if there is no noticeable pattern in the data ØThere is no relationship between the number of shirts someone owns and their annual salary
Scatter Plots – No Correlation number of shirts owned salary 1 1 2 0 3 50 4 30 5 25 6 17 7 2 8 40 9 8 10 25 11 12 12 7 13 19 14 55 15 71 16 9 Can you make a prediction based on this data?
Line of Best Fit • A line of best fit is a line that best represents the data on a scatter plot and often shows a trend in the data. Ø The line may pass through some of the points, none of the points, or all of the points. Ø The purpose of the line of best fit is to show the overall trend or pattern in the data and to allow the reader to make predictions about future trends in the data.
Lines of Best Fit and Outliers There is one point on here that would be considered an outlier because it doesn’t go with the data. Which one is it?
TWO VARIABLES • # of hours of sunshine each day • # of Visitors to certain part of the beach • What type of relationship would these variables have?
Scatter Plot of the Data I have started a scatter plot for you…finish it.
Year 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 # of Tornadoes 201 593 919 866 684 1133 1234 616 897 654 1200 1000 800 600 400 Do you notice a trend? 1995 1990 1985 1980 1975 1970 1965 1960 1955 1950 200
Use the line of best fit to predict how many tornadoes may be reported in the United States in 2015 if the trend continues. 1200 1000 800 600 2015 2010 2005 2000 1995 1990 1985 1970 1965 1960 1955 1950 200 1980 400 1975 If the trend continues we predict that there will be 1200 tornadoes reported in 2015.
Practice Problems Page 388 3 -5
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