# TI-83 Instructions

## The Regression Line and the Correlation Coefficient

- Computing the Equation of the Regression Line and the Correlation Coefficient
- Enter the
*x* values into List `L`_{1}

.
- Enter the
*y* values into List `L`_{2}

.
- Press
`STAT`

.
- Select the
`CALC`

menu title.
- Select menu item #8,
`LinReg(a + bx)`

. (Menu item #4 is similar, but I prefer #8.)
- Press
`ENTER`

. The phrase `LinReg(a + bx)`

appears in the display.
- Press
`2nd L`_{1}

.
- Enter a comma.
- Press
`2nd L`_{2}

.
- Press
`ENTER`

. The display shows the equation `y=a+bx`

as a reminder of what `a`

and `b`

stand for. It also shows the values of `a`

and `b`

. Note that `b`

is the slope *b*_{1} and `a`

is the *y*-intercept *b*_{0}.
- Below
`a`

and `b`

are displayed `r`^{2}

and `r`

.

- Graphing the Regression Line
- Follow the above steps to compute the equation of the regression line. A consequence of this is that the coefficients will be stored in the calculator. (This step is necessary.)
- Press
`Y=`

(in the upper left corner).
- Select a function variable by moving the cursor to that line, say
`Y1`

.
- Press
`VARS`

. Some menu titles appear. The `VARS`

menu title is highlighted
- Use the down arrow to select menu item #5,
`Statistics...`

- Press
`ENTER`

. The `Statistics`

menu titles appear.
- Select the
`EQ`

menu title.
- Press
`ENTER`

to select menu item #1, `RegEQ`

. This is the expression `a + bx`

that was previously calculated. It is now pasted into the function `Y1`

.
- Create a scatter diagram. When the scatter diagram is drawn, the regression line will also be drawn.