Computer = brute force
If you have clicked the button a few times, you've seen that the results vary quite a bit. Here are the first ten results that I got:
What have we accomplished so far? First, we made a hypothesis about what causes sickdays -- namely, they happen on randomly chosen days. The competing hypothesis, held by the pointy-haired boss, is that sickdays occur disproportionately on Mondays and Fridays.
|First step: pick a hypothesis|
Secondly, we calculated how many sickdays "should" fall on Mondays or Fridays according to our hypothesis -- that is, 40%, or 40 out of 100. This is the expected value of sickdays. But since we're dealing with a random process, we also expect some scatter around that expected value. The key question is, how much scatter?
|Second step: calculate the expected result|
Next we used a simulation of randomly chosen weekdays to investigate how much scatter to expect around the 40 out of 100 prediction.
|Third step: simulate the scatter|
In the 10 trials, listed above, how common was it to get 42 or more Monday/Friday sickdays?
- I need a hint ... : Try counting how many trials had at least 42 Mon/Fri sickdays
- ...another hint ... : 3 out of 10 trials had at least 42 Mon/Fri sickdays -- what percentage is that?
I think I have the answer: 3 out of 10 trials had at least 42 Mon/Fri sickdays,
or 30%, which seems pretty common.
Time for a donut break!
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