# 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.

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.

Copyright University of Maryland, 2007

You may link to this site for educational purposes.

Please do not copy without permission

requests/questions/feedback email: mathbench@umd.edu