MATH121
Linear Regression on TI-81
| 1. Enter lists | |
| Clear all statistical lists | |
| Get ready to enter data | |
| Enter pairs of x and y values, pressing |
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| Quit | |
| 2. Graph the data | |
| Clear all equations Y1 thru Y4 | |
| Use the STAT DRAW menu to graph the data points in a scatter graph | |
| 3. Do the linear regression; the equation will be of the form y(x) = a + bx | |
| On the STAT menu, go to LinReg to do the linear regression. | |
| Values of a, b, and r appear on screen b = slope; a = y intercept |
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| 4. Paste the linear regression equation into Y1 and graph it | |
| Regression equation is pasted into Y1 | |
| Now the STAT DRAW menu will sketch a graph of the regression line and the scatter plot | |
| 5. Use the regression line to make predictions | |
| If the prediction is to be made at X = 5, use the keystrokes below. Replace the 5 with the number of your choice. | |
| The number of your choice is now stored in the variable X | |
| The regression equation stored in Y1 is evaluated at the value stored in X | |