Introduction to the TI-83/TI-84 Graphing Calculators

Dr. John C. Nardo                                                    

Division of Mathematics & Computer Science                   

Oglethorpe University                                              

Atlanta, GA 30319                    
(404) 364-8327                                
jnardo@oglethorpe.edu
   
http://www.oglethorpe.edu/faculty/~j_nardo/

                      

A Data Set

 

The magazine Forbes publishes an extensive report about the wealthiest people in the United States.  One variable under study is the age (in years) of billionaires in this country.  The data set below is a random sample of such ages.

 

75

63

44

71

80

49

76

59

65

41

64

81

76

44

66

93

50

58

73

33

77

80

90

67

73

 

 

 

 

 

 

 

Entering Data

 

First, we must enter the data set we wish to explore into the calculator using the Stat Editor.  Press [STAT].  The Edit command should be selected, i.e. its label 1 should be highlighted. 

 


 


 

Use the up and down arrows to move among the other commands, if needed.  To execute the Edit command, press [ENTER].  You should now have a workspace consisting of six columns labeled L1 through L6.  Each column is a separate data set/list.

 

 

 

 

 

 

 

 

 

 

 

Use the left and right arrows to move to a column/list which is blank.  Usually, we will reuse list one (L1) for our data sets.  Type each piece of data and press [ENTER].  Continue until all data has been entered into the calculator. 

 

If you make a mistake before you press [ENTER], you may use the left and right arrows to move in the entry and retype to correct the error.  If you do not realize your error until after you have pressed [ENTER], use the up and down keys to reselect/highlight the mistaken entry and retype. 

 

If you want to erase an entry entirely, use the up and down keys to reselect/highlight the entry and hit the delete key [DEL]. 

 

When you are done typing in the data set, you will see the screen below (if you typed in the data moving across each row left to right).

 

 

 

 

 

 

 

 

 

 

 

When you type in a piece of data, the calculator notes the name of the list with which you are working and which numbered piece of data it is.  The last entry in the list (highlighted above) is marked

L1(25) = 73.  This means that the 25th piece of data in the list named L1 is the number 73.

 

When finished entering the data, you should return to the home screen by executing a “quit” command.  Press the [2nd] button and then the [MODE] button.  Note that the word quit is above the mode key in yellow; thus, to execute the quit command, you had to “shift” using the [2nd] key.

 

Sorting Data

 

Very often we need to sort the data ascending (from smallest to largest) or descending (from largest to smallest).  In order to make this task less arduous, we can use the calculator.  Let’s begin by performing an ascending sort.  Press [STAT].  Press the down arrow once to select the SortA( command. 

 

 

 

 

 

 

 

 

 

 

 

Press [ENTER] to paste this command to the home screen. 

 

 

 

 

 

 

 

 

 

 

 

Next we must indicate the list to be sorted.  We wish to sort our data set, entered as L1.  Press [2nd] [1].  Press [ENTER] once more to execute the sort.  The calculator responds with Done when it is finished.

 

 

 

 

 

 

 

 

 

 

 

Now, we may view the sorted data.  Press [STAT].  Press [ENTER] for the Edit window.  Now simply use the up/down arrow keys to scroll through the data.  (To sort descending, use the SortD command.)

 

 

 

 

 

 

 

 

 

 

Numerical Measures of Center and Spread

 

The TI-83 can construct most of the usual measures of center and spread for a given data set; in particular it can quickly calculate the mean, median, and standard deviation.  If you are not at the home screen, then execute a quit command:  [2nd] [MODE].  You should now be back at the home screen.  Press the [CLEAR] button to create a blank screen. 

 

 


 

To calculate these measures, press the [STAT] button.  Select the CALC menu by pressing your right arrow key once.  The first command in this menu should now be highlighted, as below.  The 1-Var Stats command will act on a data set containing values for one variable; 1-Var Stats is the command we need.  Your screen should look like the following:

 

 

 

 

 

 

 

 

 

 

 

 

Press [ENTER] to paste the selected command to the home screen. 

 

 

 

 

 

 

 

 

 

 

 

 

Again, we must give the data set for which we want these measures calculated.  Press [2nd] [1] to indicate the list L1. 

 

 

 

 

 

 

 

 

 

 

 

Press [ENTER] once more to execute the command. 

 

 

 

 

 

 

 

 

 

 

 

Notice that there is an arrow at the bottom of the screen to indicate another screen of information.  Scroll down with the arrow keys to see all pieces of information. 

 

 

 

 

 

 

 

 

 

 

 

Usually there are many decimal places with which we must deal; thus, we will often need to round calculations for convenience.  Here we will round all values to two decimal places. 

 

The mean of this sample is:  .

The median of this sample is:  .

The standard deviation of this sample is: 

 

Creating Histograms and Other Statistical Plots

 

We may create a graphical representation of a data set by using the calculator to generate a histogram.  Access the STAT PLOT screen by pressing [2nd] [Y=].  There are three separate plots which you may use:  Plot1, Plot2, and Plot3.  You may choose to always reuse the same plot or to switch back and forth between plots.


 

 

 

Choose a plot by using the up and down arrows to select/highlight the plot.  Press [ENTER] to carry out this choice.  The cursor should be blinking on the word On.  Press [ENTER] to turn the plot on; the word On should now be selected/highlighted. 

 

Move to the next selection/choice by pressing the down arrow.  There are six icons denoting the various types of statistical plots available on the TI-83.  The icons represent scatterplots, line graphs, histograms, modified boxplots, boxplots, and normal quantile plots, respectively.  The left and right arrows move between these choices.  Make sure that the cursor is blinking over the last icon in the first row and hit [ENTER] to select the histogram option. 

 

Press the down arrow to move to the next selection.  Now, we must choose which data set is plotted, here list L1.  To select this list, press [2nd] [1].  Now, you should see the screen below.

 

 

 

 

 

 

 

 

 

 

 

We will use the ZOOM menu to generate the histogram.  Press [ZOOM].  Press the up arrow twice to select/ highlight ZoomStat.  Press [ENTER] to execute this command.  (As a shortcut you may simply press [9] to select and execute this command simultaneously.)  The TI-83 calculator will now choose appropriate ranges of values for the axes, automatically set the “best” viewing window, and generate the histogram. 

 

 

 

 

 

 

 

 

 

 

 

We can get information from the graph by pressing the [TRACE] button. This places a blinking icon on the graph and gives information about the selected rectangle.  It tells where the rectangle stops and starts; also, it gives the height of the rectangle.  To move back and forth, press the right and left arrow keys.  The screen shot below gives information about the third rectangle from the left.

 

 

 

 

 

 

 

 

 

 

 

If your plot disappears or you make some calculations on the home screen, you can recall this plot without having to use the Zoom Stat menu.  To regenerate the graph, press [GRAPH]. 

 

If you wish to stop your current action and return to the home screen, then execute a quit by pressing [2nd] [MODE].

 

If all else fails, turn off the calculator by pressing [2nd] [ON].  Then you can turn it on

again and retry.