1. 2.6 Draw Scatter plots & Best Fitting Lines
Algebra II

2. Definitions
Scatter plot – a graph used to determine whether there is a relationship between paired data.
Positive correlation - positive slope
Negative Correlation – negative slope
Relatively No correlation – no linear pattern

3. Positive Correlation

4. Negative Correlation

5. Relatively No Correlation

6. Approximating Best Fit Line
1.) Graph scatter plot on coordinate plane
2.) Sketch a straight line in the middle of the data. Try to have equal # of points on either side.
3.) Choose two points on the line either given or discovered to find the slope.
4.) Determine the slope either with the slope formula or visually.
5.) Write the equation of the line in slope intercept form.

7. Ex. 1 Describe Correlation, Approximate best fit line

8. Ex. 2 Finding a Best Fit Line
The data pairs give the average speed of an airplane during the first 10 minutes of a flight, with x in minutes & y in miles per hour.
a.) Approximate the best fit line for the data.
(1,180), (2, 250), (3, 290), (4, 310), (5, 400), (6, 420), (7,410), (8,490), (9, 520), (10, 510) Or x 1 2 3 4 5 6 7 8 9 y
180
250
290
310
400
420
410
490
520

9. Step 1) Graph Scatter Plot

10. Ex. 2 Writing the equation of the line
b.) Write the equation of the best fit line.
(Directions read: Approximate the best-fitting line for the data. This includes giving the equation of the line.)

11. Correlation website