With the Texas Instruments TI-89, you can calculate the most commonly-used descriptive statistics for one variable (mean, standard deviation, sum of values, sum of the values-squared) and for regression/correlation between two variables (regression coefficient and intercept, correlation coefficient).

Data are entered and stored in a table
(which allows checking that you have entered correctly & keeps
the numbers for recalculation) using the Data/Matrix Editor.

To access the statistical calculations you must have Data/Matrix
editor window open (showing the data lists) [This is the reverse
of the situation with the other TI-8x calcuators]

**For the statistical calculations**:If the Data/Matrix editor
window is not open: Press APPS, highlight 6:Data/Matrix Editor,
curosor right (use arrow key) to open submenu and select 1:current
[or 2:new to open a table that you have named and saved, or 3:
New to create a new data table]. With the Data/Matrix editor window
open, press F5 for the statistical functions.

The TI-89 stores data in a Data table - each variable goes in one column (default names are c1, c2, etc. - you can rename them. See your user's guide) which is accessed using APPS followed by 6:Data/Matrix Editor, then 1:Current [or 3:New if you do not have any data saved] from the popup menu

There are three situations in which you
enter data - one variable (actual data), one variable (with frequencies
- grouped or ungrouped), two variable.

**Always clear old data from any list (column) you will use**
before entering new data, or your results will be messed up:

**To clear a column**: With the Data table showing in the window:
Use the right/left arrow keys to put the cursor in the column
to be cleared. Then press 2d-F1 [F6] (Utilities) and press 5:Clear
column [You do **not** want 2:Delete - that will remove the
column - the spaces - rather than emptying out the numbers]

## A. One variable

Open the Data/Matrix Editor: Press APPS to open the window listing applications, Select 6:Data/Matrix Editor, use the right cursor [or ENTER] to see the submenu, then if you have no data sets entered, press 3:New [If you have data saved, you can select 1:Current to reveal the most recent data lists or 2:Open to retrieve old saved data sets]

Values of the variable go in any column (c1 or c2 or any other): enter the number (you see it at the bottom of the screen), press cursor-down, enter the next, etc.

To change a value already typed in: Use the up & down arrows to highlight it, enter the new number & press the down-arrow or ENTER to put the new number in.Press F5 [Calc] to go on an perform calculations or 2nd +[ESC] [Quit] to return to the Home screen.

## B. One-variable with varying frequencies

Open the Data/Matrix Editor: Press APPS to open the window listing applications, Selet 6:Data/Matrix Editor, use the right cursor [or ENTER] to see the submenu, then if you have no data sets entered, press 3:New [If you have data save, you can select 1:Current to reveal the most recent data lists or 2:open to retrieve old saved data sets]

Values of the variable go in the one column (c1, c2, or whatever): enter the number (you see it at the bottom of the screen), press down-arrow, enter the next, etc.

To change a value already typed in: Use the up & down arrows to highlight it, enter the new number & press the down-arrow or ENTER to put the new numbber in.The frequencies (number of times repeated) for the values are entered in the any other column (best is the next column to the right) - there must be a frequency for each value.

Press F5 [Calc] to go on an perform calculations or 2nd +[ESC] [Quit] to return to the Home screen.

## C. Two-variable

Open the Data/Matrix Editor: Press APPS to open the window listing applications, Selet 6:Data/Matrix Editor, use the right cursor [or ENTER] to see the submenu, then if you have no data sets entered, press 3:New [If you have data saved, you can select 1:Current to reveal the most recent data lists or 2:open to retrieve old saved data sets]

Values go in pairs : x values in one column y-values in another (easiest to enter all x-values in one column and then y-values in another, next to corresponding x-values)To change a value already typed in: Use the up & down arrows to highlight it, enter the new number & press the down-arrow or ENTER to put the new numbber in.

Press F5 [Calc] to go on an perform calculations or 2nd +[ESC] [Quit] to return to the Home screen.

To access the statistical calculations
you must have Data/Matrix editor window open.

If you entered the data before, open the data set (in the editor):

Press APPS to open the window listing applications,
Select 6:Data/Matrix Editor, use the right cursor [or ENTER] to see the submenu,
then if you have no data sets entered, press 3:New [If you have data saved,
you can select 1:Current to reveal the most recent data lists or 2:open to retrieve
old saved data sets]

## A. One-variable

[From Dat/Matrix Editor]

Press [F5] (function key 5) , Cursor right at Calculation type to select OneVar

Cursor down and put the column name for the variable (c1 or c2 or whatever it is) in the box for x ....

Be sure the answer to "Use Frequency and Categories" question is "NO" (if it says "YES" - select it and change the response to "NO")

Press ENTER

You see a screen with mean( x-bar), sum of x's sum of x-squares ( not "sum of squares" SS(x)) sample standard deviation (Sx) sample size (nStat) - scrolling down will show minimum (minX), 1st quartile (q1), median (medStat), 3d quartile (q3), and maximum(maxX) - that is, the 5-number description.

You can close this window with ESC## B. One-variable with varying frequencies

[From Dat/Matrix Editor]

Press [F5] (function key 5) , Cursor right at Caclulation type to select OneVar

Cursor down and put the column name for the variable (c1 or c2 or whatever it is) in the box for x ....

Be sure the answer to "Use Ferquency and Categories" question is answered "YES" (if it says "NO" - select it and change the response to "YES")

Enter the name (c1, c2 or whatever) of the column containing the frequencies in the box for "Frequency". Leave the other boxes empty

Press ENTER

You see a screen with mean( x-bar), sum of x's sum of x-squares ( not "sum of squares" SS(x)) sample standard deviation (Sx) sample size (nStat - this will be the sum of the frequencies) - scrolling down will show minimum (minX), 1st quartile (q1), median (medStat), 3d quartile (q3), and maximum(maxX) - that is, the 5-number description.

You can close this window with ESC## C. Two-variable

Regression/correlation[From Dat/Matrix Editor]

Press [F5] (function key 5 - at the left) , Cursor right at Caclulation type to select 5: LinReg [Watch out - you don't want #6 which is LnReg - logarithmic regression]

Cursor down and put the name (c1, c2, whatever) of the column containing the independent variable (the predictor) in the box for x, put the name of the column for the dependent variable (response) in the box for y.

Be sure the answer to "Use Ferquency and Categories" question is answered "NO" (if it says "YES" - select it and change the response to "NO")

Press ENTER

You see window giving form of equation: y = ax + b, [so you can see which number is which], then values of a (coefficient), b (intercept), correlation coefficient (corr) and coefficient of determination (R^2).

Note:To save the regression equationfor graphing, use the "Store RegEQ to" line to select a function name (y1, y2, etc.) which will hold the equation for graphing.## Combined statistics

[From Dat/Matrix Editor]

Press [F5] (function key 5 - at the left) , Cursor right at Caclulation type to select 2: TwoVar

Cursor down and put the name (c1, c2, whatever) of the column containing the independent variable (the predictor) in the box for x, put the name of the column for the dependent variable (response) in the box for y.

Be sure the answer to "Use Frequency and Categories" question is "NO" (if it says "YES" - select it and change the response to "NO")

Press ENTER

You to see a screen giving mean of data in x-list (x-bar), sum of x-list data ( sum of x's) sum of x-squared ( not "sum of squares" SS(x)) sample standard deviation for x-list (Sx), then same data for y-list (called y on screen) and the sum of the xy's .

The TI-89 will produce boxplots or histograms from one-variable data, and scatter plots from 2-variable data. Several plots can be defined at one time.

To define a plotPress APPS and select 2:Y= Editor

Turn off the functions defined in the editor [unless one is a regression line you want to plot] so the calculator will not try to graph them with your plot.

Cursor up past y1 = to see Plot1:[up past Plot 1 for Plot , etc.] Select this to define the plot.

Select the plot type. by using the right cursor and the number.

For a Box Plot or histogram you must enter the name of the column containing the data. If you do not have a frequency column (case B under data entry) make sure the answer to "Use Freq and Categories?" is "NO". If you do have frequencies, enter the name of the frequency column in the box.

For a scatter plot you must enter the column names of the columns containing the x- and y- variables. Be sure the answer to "Use Freq and Categories?" is "NO" [unless you have a third column with frequencies]

Press ENTER to save the plot commands and return to the Y= Editor

To see your plot,

Press F2 to open the "Zoom" commands.

Select 9:Zoom Data or set the x-range to match the range on x & y-range to match the range on y(y-range to contain frequencies, for a histogram)

Press ENTER

If you define (and turn on) a scatterplot and calculate the regression line with the same data (using the command that saves the line to y1) the line will appear on the plot when you give the "graph" command.

Errors or questions? Please let me know: cpeltier@saintmarys.edu

Last update 2/10/2009