Sometimes it is the easiest of tasks that takes the longest time. In my Statistics classes we cover the Chi-Square (Goodness of Fit) test to see if there is a significant difference between observed and expected values. It is one of the easiest statistics tests to do - all you need are two values and then be able to add, subtract, divide, and square a number. So when I decided to record this I though maybe one or two takes would see me through. 27 takes later I recorded the version below which is now on YouTube. Somehow I got tongue-twisted and made small errors, especially with the calculator. As with all of my short videos (this one in 7 mins 32 secs), if I make an error I simply discard and start again. So what should have taken less than half an hour probably took about four hours to do!