MathBench > Statistical Tests

Chi-square Tests

Give it a try

fish taking a lureOn the form below, you can put this all together. As you fill out each column, click on the button below it to check your numbers. BTW, this is where having a calculator will come in handy. As long as you use 2 significant digits in your calculations, the program will fill in additional digits for you.

Once again, recall that there were 42 mon/fri sick days out of 100.

observed ("o") expected ("e") (o-e) (o-e)2 (o-e)2/e
Mon/ Fri
Midweek
Total 100 100    
Check

 

So now you have calculated a number which is the chi-square statistic for this test, also called the "chi-square-calc". It's the one that's obnoxiously flashing at you. But what do you DO with it? You know that a big chi-square-calc is bad (because it means that the data deviate a lot from the model) and a small chi-square-calc is good (because it means the data doesn't deviate). But how big is big, or how small is small?

roadmap

 

detour signBefore we answer that question, we need to take a brief detour to discuss degrees of freedom. After that, we can finally answer the question, are Dilbert's colleagues really out fishing on their long weekends?