Regression Lines

Regression Lines

1. Setup the scatter plot as instructed above
2. Go into the Stats, Calc, Setup screen
3. Setup the 2-Var Stats so that: Xlist = L₁, Ylist = L₂, Freq = 1
4. Calculate the Linear Regression (ax+b) (#5)
5. Go into the Plot screen.
6. Position the cursor on the Y1 plot and hit CLEAR to erase it.
7. While still in the Y1 data entry field, go to the VARS, STATS, EQ screen and choose option 7 which is the regression equation
8. Hit GRAPH

The above technique works, but it requires that you change the equation being graphed every time you change problems. It is possible to stick the regression equation "ax+b" into the Y1 plot and then it will automatically graph the correct regression equation each time.

Do this once

1. Setup the scatter plot as instructed above
2. Go into the Plot screen.
3. Position the cursor on the Y1 plot and hit CLEAR to erase it.
4. Enter a*x+b into the function. The a and b can be found under the VARS, STATS, EQ screen

Do this for each graph

1. Go into the Stats, Calc, Setup screen
2. Setup the 2-Var Stats so that: Xlist = L₁, Ylist = L₂, Freq = 1
3. Calculate the Linear Regression (ax+b) (#5)
4. Hit the GRAPH key

It is important that you calculate the linear regression variables before trying to graph the regression line. If you change the data in the lists or have not calculated the linear regression equations, then you will get an " ERR: Undefined" when you try to graph the data.