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Topic: Standard Deviations From Expected Values History
Replies: 18   Last Post: Sep 4, 2012 2:53 PM

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Douglas 73

Posts: 52
From: Pacific northwest, USA
Registered: 1/15/11
Standard Deviations From Expected Values History
Posted: Jul 15, 2012 9:04 PM
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I have an ongoing random variate statistical sampling study which stands at
4,100 items selected and recorded as of now. The items come to me in
variable quantity sets. After data entry from each set, I calculate their
current standard deviation (SD) from the generally accepted expected mean.

Here is a summary of these SD values to date:

2.32 @ 219 items
3.08 @ 571
4.33 @ 669
5.06 @ 836
6.05 @ 1,804
6.12 @ 2,107
Then a steady decline to:
4.45 @ 2,633 items
Since then to now, the values wander about like a drunk from 4.26 to 4.73.
Today's SD value is 4.53.

Has anyone experienced SD values with any sort of history like this before?


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