Here is what your table should have looked like.

The question in the Key Problem was, do more accidents occur at certain hours or was that just the data just a probable random occurrence?

The c2 obtained was 5.1. Is this statistically significant is the real question that the Key Problem is asking, in mathematical terms?

Use the following spreadsheet to generate many c2's so you can see where 5.1 lies in a random pool and see how likely it is to occur by chance. Do this for yourself, or be feeble and just use the example below.

As you can see, 5.1 falls well within the middle values of the table. Now look at this graph.

5.1 is well to the left side of the graph, which means it is not statistically significant. So your answer to the union at the Irongate Foundry would be that there is no difference for when the accidents happen during a shift.

Is that good news or what?

Try these two problems if you think you have the hang of Chi-Square.

Bulls Chi-Square Problem

Challenge Problem

You have finished this lesson, how do you feel? Like Bill the Cat? Hopefully not.

You are now armed with the Chi-Square which will be by your side when you need to make those all important decisions. Good luck.