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USING THE TI PROGRAMMABLE CALCULATOR FOR STATISTICS

The IB Biology programme expects you to be able to calculate and understand a number of statistical parameters and tests. The calculator can take some of the hard work out of this process but you still need to understand why you have decided to use a particular test and what it means.

Use the key

Press

This gives you the STAT menu

You will already be in the EDIT menu. Press

This opens a spread sheet

You can see if there is anything stored in the columns of the spread sheet. Check this and if there are data you need to clear it.
  • To clear the spread sheet
Press
You will be in the EDIT menu. Press
You will get "ClrList"
Press then


You have now cleared column L1
Repeat the process (, , , , etc….) to clear the other columns
  • To enter data
Press
You will be in the EDIT menu.
Select
This opens a spread sheet
type in the first number, then
second number then
etc

If you are comparing two sets of data do the same thing in column L2
  • To find out mean, median, standard deviation and more besides!
Press
Use the cursor to move across to the CALC menu
You will find a menu which permits you to calculate a large number of statistical parameters. Most of what we want is in 1:1-Var Stats, the first on the list.


Press
1-Var Stats appears
Press then and
You will get:

the mean
Sx (the standard deviation of the sample)
s x (the standard deviation of a population)
n (the number in the sample)

Scroll down for more!

Med (the median)

  • To calculate the t-test

Press
Use the cursor to move to the TESTS menu
Press
This selects 2-SampTTest

You will probably find the data has already been entered for L1 and L2 but if you want to use another column of data change the Lists by scrolling down.
 Scroll down further to select CALCULATE
Press
You will get the result for the t-test on your data
t = …….

Now using the correct Degrees of Freedom and the probability table for the t-test, you can find if the t value you have calculated lies above or below the critical 5% probability level (p=0.05). You will either accept the Hypothesis (There is a significant difference…) or the Null Hypothesis (There is no significant difference…).

Using the calculator as a counter
If you want to count an event without taking your eyes away from it, it is convenient to have a counter.

Press





+







etc

© Paul Billiet 2004