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, Evil Pointy-Haired Boss (EPHB) finds that 42% 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 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%?
Or, what if next year 90% of sickdays fell on Monday or Friday? Would that make you think that Dilbert was wrong, and sick-days were not random? What about 50% of sickdays on M/F?
When you do statistics, you are doing two things: first, putting numbers on common sense, and secondly, using a method that allows you to decide on the gray areas. So, what we expect out of statistics is the following:
- if 40.1% of sickdays are M/F: statistics tells me this fits the random sickday model
- if 50% of sickdays are M/F: statistics allows me to make a decision about this "gray" area
- if 90% of sickdays are M/F: statistics tells me this does not fit the random sickday model
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