Mean and Standard Deviation on a TI85
Here's how to compute some basic statistics on your TI85:

Press the [STAT] button. You should see something like
this on your screen:

Press the [EDIT] button (that is, press the button on your
calculator below the box labeled "EDIT" on the screen). Now your
screen should look something like:

Press [ENTER] twice to indicate that you will keep your
data in the list(s) xStat and yStat.

Don't worry about this  we will always use the same names.

If by some chance the screen shows some other entries for "xlist Name"
or "ylist Name", you can always find
xStat and yStat
on the bottom menu on the screen, and reenter them as list names. If needed,
press the [MORE] button to get xStat and yStat
on the bottom menu.

Now your screen should look something like this:
or
. If there are numbers already entered for x1, etc, clear them
out by pressing [CLRxy] from the bottom menu, so that you have
the second picture above.

Now type in your list of numbers, pressing [ENTER][ENTER]after
each one. The idea of pressing [ENTER]twice is that we
want our data values only on the "x" lines. The "y" lines
should have "1" in them. For instance, if your list of numbers
is {1,3,4,5,7}, then when you are done, your screen should look
like this:
[Note: You do not have to enter the numbers in order]

Check over your list and make sure you have typed it correctly. You can
delete or insert entries with the [DELi] or the
[INSi]
keys from the screen's bottom menu. You can scroll through the entries
using the
and
keys.

Now we are ready to Calculate some statistics, so press [2nd][CALC]
to get the calculate menu:
Again press [ENTER] twice to indicate that your data
is in the list(s) xStat and yStat. Then the screen will
change slightly to:

Now press [1VAR] to indicate you want to calculate
some onevariable statistics for your list. The screen now looks
like:

The =4
tells you the mean of your list is 4. The x=2
tells
you the [population] standard deviation of your list is 2.
Short summary:

To Enter data: Press [STAT] and select EDIT
to enter your list of numbers. For what we do in this class, always using
xStat
and yStat will be fine. Use [CLRxy] if needed
to clear out old data. Remember to enter your numbers on the "x" rows and
leave the y's equal to 1.

To Calculate some Statistics: press [2nd][CALC]
and [ENTER] twice to use the xStat/yStat lists.
Press 1VAR to calculate.
Test yourself:
Try to get the mean and standard deviation of 37.75, 38, 37,
38.5, and 37.5. You should get a mean of 37.75 and a standard deviation
of 0.5.
Bonus Topics:
Frequency tables:
If you have many repeated data items, such as a frequency table:
data item 
frequency 
3

4

8

5

1

7

5

1

...meaning that your list contains four 3's, five 8's, etc., then you
can enter the data items as x's and the corresponding frequencies as y's
on the EDIT screen. For this list, you would start like this:
Finish entering the data, then ask the calculator to calculate 1variable
statistics as before:
Help with medians:
Once you type a list of numbers into the data editor (see steps #1 #6
above):
you can press [SORTX] and you will find the x's are now
displayed in ascending order, making it easier to pick out the median.
Last Modified January 31, 2000.
Prof.
Janeba's Home Page  Send comments or questions to: mjanebawillamette.edu
Department
of Mathematics  Willamette
University Home Page