The correlation coefficient is r in the linear regression output on your graphing calculator. Is it positive or negative?
Line of best fit: y=-0.45x+4.26 Correlation coefficient: r=0.67
This is a weak, negative correlation.
Practice makes perfect
Let's begin by entering the data into our calculator and using the linear regression analysis tools. If you need more explanation on how enter the data into a calculator, please look at the end of this exercise.
We can substitute the values of a and b, rounded to two decimal places, into y=ax+b to get the equation for the line of best fit.
y=-0.45x+4.26
The value of r in the calculator output gives us the value of the correlation coefficient.
r=0.668856≈0.67
This tells us that correlation is negative and weak. We can tell that it is weak because it is not close to -1. A correlation of 1 would be a direct correlation explained by a line that goes through all of the points. We can see that it is not the case by plotting the data points and graphing the line on the same coordinate plane.
Showing Our Work
Plotting the data points and graphing the line on the same coordinate plane
Looking at the given graph, we need to enter all of the x-coordinates and y-coordinates of the graphed points into the calculator. The coordinates of one point should be in one row. In the first column we should write its x-coordinate, and in the second row we write the y-coordinate. The third column should stay empty.
With this entered, we can use the linear regression feature to find the line of best fit.
