OpenIntroOrg Chi-Square Goodness of Fit Test using Casio fx-9750GII

Learn how to perform chi-square goodness of fit tests on a Casio 9750 graphing calculator.

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Approximate script:

We'll cover how to run a goodness-of-fit test. We'll need to do a couple things before we start:

1. Enter the observed data into a list: for our data set, 28 is in the first bin, 18 in the second, and 24 in the third, and 30 into the fourth.

2. Next, we enter the expected values of each bin into the list. Here we expect the four bins to have equal probability and there are 100 observations, so we expect a count of 25 in each bin.

Alright, now we can jump into Test, choose Chi for chi-square test, and then choose G-O-F for goodness of fit, which is the same as a one-way chi-square test. We specify which list is our observed data by hitting F1 for list and then entering the list number, which was 3; we do the same for our expected data list and specify 4; we also must specify the degrees of freedom, which in this case is 3, which is from the number of bins minus 1; and finally we also specify a list where the contribution to the test statistic will be reported, and I'll use List 5.

Hitting execute runs the test, and we get a test statistic of 3.36 and a p-value of 0.34. You can also double-check your degrees of freedom here and see which list to look in for the contribution of each bin to the test statistic. Let's hop out to the list view to see the contribution list. For example, here the contribution of the first bin was 0.36. We can show that manually by taking 28 minus 25, square that, and then divide by 25, which is 0.36.

Also, if you want to see a graph that visualizes the p-value, you can hop back into the test view for chi-square goodness of fit, scroll down to Execute, and then hit F6 for Draw. That shaded region represents the p-value.

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Chi-Square Goodness of Fit Test using Casio fx-9750GII
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