FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Science and Technology » Chem » Analytical
Algebraic computation of the Hat diagonal
Post new topic   Reply to topic Page 1 of 1 [1 Post] View previous topic :: View next topic
Author Message
timothyfoley_NENSP@yahoo.
science forum beginner


Joined: 23 Apr 2006
Posts: 2

PostPosted: Sun Apr 23, 2006 10:09 pm    Post subject: Algebraic computation of the Hat diagonal Reply with quote

I would like to compute studentized residuals for predicted
concentrations in assays that use first order and second order
polynomial regression, as well as non-linear 4-parameter logistic
models.

Does anyone have an algebraic solution that can be used in Excel to
compute hii in these applications. I would like to use studentized
residuals to assess the prediction quality of calibration models used
in biomedical assays.


Basically, I would like to compute the following:


t = Cal (actual) - Cal (estimated)/RMSE * SQRT (1- hii).


RMSE is computed as SQRT [Sum (cal actual - cal estimated)^2/n-p]


The Hii statistic would adjust the ratio in the preceding equation for

leverage. Calibration points with t values that are greater than 2.5 or

3 would be candidates for elimination from the the current calibration.



I was initially going to ignore leverage issues, but since many of the
calibrations I deal with have a wide dynamic range, I thought I would
include hii in the estimate of t.


The main issue is that I need to find an algebraic approximation for
the matrix operations for ease of use. Can anyone supply formulas or
better yet a macro? Advice from the chemometrically inclined would be
most welcome.


Thanks,
Tim
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 1 of 1 [1 Post] View previous topic :: View next topic
The time now is Tue Aug 22, 2017 11:08 am | All times are GMT
Forum index » Science and Technology » Chem » Analytical
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts Question from an old algebraic topology qualifying exam melanie Math 5 Thu Jul 13, 2006 1:38 am
No new posts Simplifying Algebraic expression Jeffrey Spoon Math 4 Wed Jul 12, 2006 3:04 pm
No new posts Algebraic Structure Name Confusion jpawloski@gmail.com Math 2 Mon Jul 10, 2006 2:12 pm
No new posts function semi-algebraic over real closed sub-field? Martin Ziegler Research 0 Sat Jul 08, 2006 8:17 am
No new posts help with symbolic matrix computation in maple csviks Symbolic 0 Fri Jul 07, 2006 8:58 pm

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Electronics forum |  Medicine forum |  Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums  |  send newsletters
 


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.0602s ][ Queries: 16 (0.0442s) ][ GZIP on - Debug on ]