2.6 Draw Scatter plots & Best Fitting Lines Algebra II
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
Positive Correlation
Negative Correlation
Relatively No Correlation
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.
Ex. 1 Describe Correlation, Approximate best fit line
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
Step 1) Graph Scatter Plot
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.)
Correlation website http://www.regentsprep.org/Regents/math/ALGEBRA/AD4/scatter.htm