Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.stat.math.independent

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

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Douglas 73

Posts: 22
From: Pacific northwest, USA
Registered: 1/15/11
Standard Deviations From Expected Values History
Posted: Jul 15, 2012 9:04 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

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?

Douglas




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.