Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the...

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Investigating Scatter Plots

Transcript of Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the...

Page 1: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

Page 2: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

Weight Loss Over Time

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Days worked out per month

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How shirts affect salary

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Shirts Owned

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How Study Time Affects Grades

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Page 3: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

• 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.

Page 4: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

• Positive correlations occur when two variables or values move in the same direction.

As the number of hours that you study increases your overall class grade increases

Page 5: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating 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

How Study Time Affects Grades

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Time in hours

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Page 6: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

• Negative Correlations occur when variables move in opposite directions

As the number of days per month that you exercise increases your actual weight decreases

Page 7: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots – Negative Correlation

Weight Loss Over Time

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Days worked out per month

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Weight

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

10 100

10.5 120

11 90

11.5 90

12 80

Page 8: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots

• No correlation exists if there is no noticeable pattern in the data

There is no relationship between the number of shirts someone owns and their annual salary

Page 9: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Investigating Scatter Plots – No Correlation

How does your wardrobe affect your salary

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number of shirts owned salary

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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

Page 10: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Line of Best Fit

• A line of best fit is a line that best represents the data on a scatter plot.

• A line of best fit may also be called a trend line since it shows us the trend of the data

The line may pass through some of the points, none of the points, or all of the points.

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.

Page 11: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Use the data to create a scatter plot

SandwichTotal Fat (g)

(X)Total Calories

(y)

Hamburger 9 260

Cheeseburger 13 320

Quarter Pounder 21 420

Quarter Pounder with Cheese 30 530

Big Mac 31 560

Arch Sandwich Special 31 550

Arch Special with Bacon 34 590

Crispy Chicken 25 500

Fish Fillet 28 560

Grilled Chicken 20 440

Grilled Chicken Light 5 300

Page 12: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Scatter Plot of the Data

Fat Grams and Calories in Food

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Total Fat Grams

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Page 13: Investigating Scatter Plots. Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot.

Things to remember

• A scatter plot with a positive correlation has X and Y values that rise together.

• A scatter plot with a negative correlation has X values that rise as Y values decrease

• A scatter plot with no correlation has no visible relationship

• The line of best fit is the line that best shows the trend of the data