# 3: The day is saved … or not

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

But wait. What if next year, the Evil Pointy-haired Boss (EPHB) finds that 42% of sick days 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 the 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%?

Or, what if next year 90% of sick days fell on Monday or Friday? You would probably appeal to common sense to say  that Dilbert was wrong, and sick-days were not being taken randomly, because 90% is so much more than 40%. What about 50% of sick days on Monday or Friday? Would that be enough to suggest there is bias toward taking sick-days on Monday or Friday?

Statistics provides numbers that we expect to align with common sense, and provides a method for interpretation of grey areas. So, what we expect out of statistics are the following:

• If 40.1% of sick days are Monday or Friday: statistics confirms that this most likely fits the random sick day model (not a grey area).
• If 50% of sick days are Monday or Friday: statistics helps me to make a decision about this “grey” area.
• If 90% of sick days are Monday or Friday: statistics confirms that this most likely doesn’t fit the random sick day model (not a grey area).