1. 1.6 Scatter Plots and Lines of Best Fit
Objectives: Interpret data in a scatter plot. Find a line of best fit on a scatter plot by inspection.
Standard Addressed: C: Fit a line to a scatter plot of two quantities and describe any correlation of the variables.

2. Scatter plots provide a picture of the relationship between two sets of data.
Scatter plots and lines of best fit can be used to predict relationships and future occurrences.
A scatter plot shows how 2 variables relate to each other by showing how closely the data points cluster to a line. Scatter plots provide a convenient way to determine whether a relationship exists between 2 variables.
The relationship is called a correlation.
A positive correlation occurs when both variables increase.
A negative correlation occurs when one variable increases and the other variable decreases.

3. Ex. 1

4. Ex. 2 Think of 2 examples of related data
Ex. 2 Think of 2 examples of related data. Describe the kind of correlation you expect from the data and why.
Age color vs. Hair  No Correlation
Age Car vs. Value $  Negative Correlation
Study vs. Grade  Positive Correlation

5. Finding Lines of Best Fit
Scatter plots can be used to show trends in data. When the points in a scatter plot are represented by a trend line or line of best fit, you can study the line to see how the data behave. You may have a basis to predict what the data might be for values not given.

6. Ex. 3 Calculator and Years!! Y = 15.9x -371.8
1950
1955
1960
1965
1970
1975
1980
1985
1990
# of storms
200
600
620
900
650
920
880
700
1180
Y = 15.9x
R = .80 Moderate Positive Correlation

7. Ex. 4
Y = 5x – 430.6
R = .997 Strong Positive Correlation

8. 11.