3: The day is saved . or not

Apparently we have saved the day. 40% of sickdays SHOULD fall on Monday or Friday, which means that
employees are not abusing the system.

dilbert cartoon

But wait. What if next year, Evil Pointy-Haired Boss (EPHB) finds that 42% sickdays fell on Monday or Friday???
Proof positive, in his view, that employees are out to get him.

Let’s be Dilbert for a minute. How could we confirm or disprove Evil Pointy-Haired Boss (EPHB’s) claim?
Clearly 42% is more than 40% — but how much is too much? Do the extra 2% just represent the natural
“slop” around 40%?

In fact there are (at least) two ways to do this:

1. The Brute Force method: make up (“simulate”) lots of data. This is conceptually not too hard,
but it requires a lot of computation.

2. The Statistical method: chi-square test. This is conceptually harder, but requires only basic
arithmetic, a calculator, and a lookup table to implement.

We’ll try them both, and you can see which one you like better.