At 4:58 PM -0400 9/2/03, Hildreth, Bruce wrote:
Hi Bruce, see embedded comments
-----Original Message-----
From: Bruce Jackson [mailto:[EMAIL PROTECTED]
Sent: Tuesday, September 02, 2003 3:37 PM
To: [EMAIL PROTECTED]
Cc: Bruce Hildreth
Subject: Confidence interval
During this month's working group telecon, the topic of confidence intervals for aero data came up. I think I misspoke then about using a single value for "confidence," and wanted to clarify my thoughts.The current draft AIAA standard for simulation data exchange
<http://dcb.larc.nasa.gov/utils/fltsim/DAVE/AIAA_stds/SimDataExchange_Jan2003.pdf>
recommends carrying, for any data table so desired, a set of points showing the 95% confidence bound (with the table values themselves being the nominal value to use if not performing a Monte Carlo or stress test).I[Hildreth, Bruce] thought 3 sigma was 95%. However, the confidence interval info should support symmetric and assymetric distrubutions of any confidence, We should add to the DTD;1)global distrubution specification definition ( ex. normal, binomial, uniform... etc)2)global sigma (accuracy) specification (ex. 1, 3, 5 whatever... etc)and the related two DTD for a specific function that overrides the global definitionI do not believe that the spec should require a specific definition, but needs to accomodate whatever the data is. So I think we agreeNote: for symmetric distributions only one value needs to be set, Only for assymetric distributions do you need the + and the -.
I am posting this reply to [EMAIL PROTECTED] so others may
benefit from your wisdom, Bruce H. :).
I don't see an exceptional utility to a global distribution
specification; this is only a small amount of data to append to each
table. I agree we need both a distribution specification and an
accuracy specification (the popular "six sigma" will be the
favorite of management types!) but I think it is best left to reside
with individual tables.
--
Bruce Jackson mailto:[EMAIL PROTECTED] Dynamics and Control
Branch
18C West Taylor Street MS 132 Airborne Systems Competency
NASA Langley Research Center Building 1192C, Room 149
Hampton, VA 23681-0001 scud://N 37 05'31.7" W 76 22'55.1"
http://dcb.larc.nasa.gov/DCBStaff/ebj/ebj.html "There is no try"
18C West Taylor Street MS 132 Airborne Systems Competency
NASA Langley Research Center Building 1192C, Room 149
Hampton, VA 23681-0001 scud://N 37 05'31.7" W 76 22'55.1"
http://dcb.larc.nasa.gov/DCBStaff/ebj/ebj.html "There is no try"
