Analysis skills, not so much

Something was nagging me all day yesterday about the recent post with the 2009 stats. “DTs,” said I to myself, “You are slothful, it is true. Yet there is no way that twenty-four shifts of yesteryear went by with one call each, nor 42 shifts with only two calls each. Not to mention those shifts where our gluteus maximi were giftwrapped and given us by dispatch. You are a poor statistician and must be punished.”

DTs partner looked stonily ahead. There was no way he was being drawn into this discussion.

It occurred to me that the problem was: Our shifts run from 06:00 to 06:00. Therefore, a scant 18 hours into my shift, it is midnight – lo, a new day dawns. And the spreadsheet clicked over as well. On 24 occasions, we ran a single call after midnight, and then nothing afterward. Thus are mighty statistics humbled.

A quick formula change – “if the dates are the same, fine, keep counting, but if they change, check to see if it’s before 06:00; if it is, same shift” – results in the following, more lifelike volume statistics:

Calls per Shift Number of Shifts this Occurred
3 2
4 5
5 5
6 10
7 19
8 17
9 11
10 13
11 8
12 5
13 1
15 2
17 1

Statistically, you’ll note that this table supports the distribution one would expect for an average call volume of 7.85 calls – 817 divided by 104 shift-days.  Sorry for the confusion.


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