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How to Graph and Update a Regression Equation

You can view the graph of a regression equation on the TI-Nspire Graphs page and even change the data and have the TI-Nspire update the equation automatically. To view the graph of your regression equation, follow these steps:

  1. Move back to the Graphs page. If you hid the entry line, press [CTRL][G] to bring it back into view. Also, change the entry line to Function by pressing [CTRL][MENU]→Graph Type→Function or [MENU]→Graph Type→Function.

    Recall that you configured the regression dialog box to save the regression equation to f1.

  2. Press

    image0.png

    until your regression equation appears, as shown in the first screen.

  3. Next, press [ENTER] to activate the graph of the regression equation, as shown in the second screen.

    image1.jpg

TI-Nspire allows you to add or revise data and then update the regression automatically. Here is what you do:

  1. Move your cursor to column A and press [CTRL][1] to jump down to the bottom of the list.

  2. Type 106 in cell A12 and 37.5 in cell B12.

  3. Move back to the Graphs page and compare the results shown here with those from the original regression.

    Although the change is subtle, you can clearly see that the scatter plot and regression equation have changed. Also, take a look at the regression results located in columns D and E of the Lists & Spreadsheet page. The regression results have been updated there as well.

    image2.jpg

If you use the Sequence command in the column A formula cell to generate the X List data and then try to add data at the bottom of the list, you see the following warning:

This operation will overwrite data in the current column. Do you wish to proceed?

Pressing [ENTER] (indicating yes) deletes the existing column data and replaces it with zeros. Instead, use the Fill method for generating the first 11 terms of the sequence. Then, manually add 2006 to the list.

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