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Hi and welcome to another edition of hackingmaths.
Today’s lesson is to perform a Chi-squared test of independence.
This method will calculate the Chi-squared value, the p-value and the number of degrees of freedom.
So grab your calculator and follow along with the calculation.
On the right hand side you can see the “observed” contingency table.
To calculate the Chi-squared value we need to enter this table into the calculator.
So let’s begin.
We start by pressing 2nd and then x to the minus one. This takes you in to the MATRIX menu.
Once here we scroll across to the right so EDIT is highlighted and press ENTER.
You now need to enter the number of ROWS and then the number of COLUMNS that the observed table has.
Note we do not include the total rows and columns.
That means there are two rows, so we press 2 and then ENTER.
There are two columns, so we press 2 and then ENTER.
Now we need to put the values into the observed table on the calculator.
So we just type the numbers in and press ENTER after each one.
Now that you have filled in the table we can calculate the Chi-squared value.
Press the STAT button on the calculator.
Scroll all the way to the right so that TESTS is highlighted.
Then scroll up so until you get to Chi-squared Test and make sure it is highlighted.
Note that there is also Chi-squared GOF Test. You don’t want to use that.
So just highlight Chi-squared like I have done, then press ENTER.
The calculator gives you some options but you don’t need to worry about them just now.
Press ENTER 3 times,
and, if you have followed what I have done
then you will get the chi-squared value, the p-value and the number of degrees of freedom.
Well that's all for this lesson. I hope to see you next time on hackingmaths.