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Viktor Witkovsky

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Institute of Measurment SAS

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18 Feb 2014 hpmixed REML based fitting of the linear mixed effects models with a simple variance covariance structure Author: Viktor Witkovsky statistics 33 0
05 Jun 2013 NCTCDFVW Alternative algorithm for computing the CDF of the noncentral Student's t-distribution Author: Viktor Witkovsky statistics 13 0
08 Apr 2013 ToleranceFactor ToleranceFactor computes the exact tolerance factor for the two-sided tolerance interval Author: Viktor Witkovsky statistics, measurement 21 2
19 Mar 2013 DDFMIXED Estimates the denominator degrees of freedom (DDF) of the F-test in simple linear mixed model (LMM) Author: Viktor Witkovsky statistics 17 0
14 Nov 2009 Screenshot PoissRatioCdf Computes the cdf and/or the pmf of the ratio of two independent Poisson random variables Author: Viktor Witkovsky statistics, measurement 15 0
Comments and Ratings by Viktor
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14 Mar 2014 ToleranceFactor ToleranceFactor computes the exact tolerance factor for the two-sided tolerance interval Author: Viktor Witkovsky

@Pete: The presented result of ToleranceFactorGK(30,.95,.95) = 2.5549 (2.554892813277693) is in good agreement with the factor K = 2.555 from Table B2 in Krishnamoorthy & Mathew (2009, p. 368), as well as with the numerical output of R package tolerance:
K.factor(30, P = 0.95, side = 2, method = "EXACT", m = 50) = 2.554893.

The problem with many other sources is that they are based either on approximations or on not well documented method/algorithm.

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14 Mar 2014 ToleranceFactor ToleranceFactor computes the exact tolerance factor for the two-sided tolerance interval Author: Viktor Witkovsky Witkovsky, Viktor

@Pete: The presented result of ToleranceFactorGK(30,.95,.95) = 2.5549 (2.554892813277693) is in good agreement with the factor K = 2.555 from Table B2 in Krishnamoorthy & Mathew (2009, p. 368), as well as with the numerical output of R package tolerance:
K.factor(30, P = 0.95, side = 2, method = "EXACT", m = 50) = 2.554893.

The problem with many other sources is that they are based either on approximations or on not well documented method/algorithm.

14 Mar 2014 ToleranceFactor ToleranceFactor computes the exact tolerance factor for the two-sided tolerance interval Author: Viktor Witkovsky Pete

Prima facie, this looks well written and well documented. It seems to give results that are highly correlated with, but slightly from, various websites (all of which agree with each other). For example:

>> ToleranceFactorGK(30,.95,.95)
ans = 2.5549

Whereas the following all give it as 2.549
- http://statpages.org/tolintvl.html
- http://www.astm.org/standardization-news/data-points/statistical-intervals-part-3-nd11.html
- http://www.webapps.cee.vt.edu/ewr/environmental/teach/smprimer/intervals/interval.html

The difference is small though, particularly at large N, and any fault may lie with the websites rather than this function (unsure). Any explanation for this difference would be much appreciated.

Thanks for posting

29 Sep 2012 mixed Estimates the parameters of mixed linear model. Author: Viktor Witkovsky Zhu, Junqi

very good program!

29 Jun 2009 mixed Estimates the parameters of mixed linear model. Author: Viktor Witkovsky Leiva, Marcelo

Thank you for this matlab turbo. Some one have any example that show the function of "mixed"?
Thank's

10 Oct 2006 mixed Estimates the parameters of mixed linear model. Author: Viktor Witkovsky C, J

Great program. Thank you for distributing it freely.

We checked its consistency with SAS Proc Mixed (type=un), and it works.

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