Sunday, March 2, 2008

Statistics and TI89 Calculator

I am doing first year statistics at Auckland University. Because I am also doing Maths108, I decided to invest in a TI89 calculator.

The TI89 is a great calculator - but it takes a bit to learn how to drive it. I decided to sit down over the mid term break and work out the easiest way to do some of the calulations required for statistics. There are probably other ways to do the calculations - but these notes work well for me.

Quick calculations

Sometimes it is quicker to quickly define a set of values instead of using the Matrix Editor. By using the STO-> button on the calculator, you can store a set of values into a variable.

{17,20,13,45,55,26,57,79} -> list1

Now we have a variable called "list1" that we can use in future calculations

To get the mean


To get the standard deviation


To get the median


To list all other statistical values

This requires two commands. The first command calculates the required results. The second command actually displays the results

OneVar list1

Entering frequency tables

Frequency tables are entered in the same way as simple lists. To enter a frequency table, you will need to create two variables. The first variable holds the values and the second variable holds the frequencies.

Value Freq
17   1
20   3
13   2
45   3
55   4
26   5
57   2
79   1

{17,20,13,45,55,26,57,79} -> list1
{1,3,2,3,4,5,2,1} -> freq1

To find the mean of a frequency table


To get the standard deviation of a freq table


To get the median of a frequency table


Entering a frequency table with a range of values

Value Freq
10-12   1
12-14   3
14-16   2
16-20   3

When presented with a frequency table with a range of values (eg Size 10-12), use the values in the middle of the ranges. eg {11,13,15,18}

No comments: