Yayati
☆    

2008-08-05 07:04
(4639 d 00:55 ago)

(edited by Yayati on 2008-08-05 07:25)
Posting: # 2144
Views: 11,876
 

 Lund's outlier test [Design Issues]

Dear All,
When we used Lund's outlier test?
I heard it is used to detect outlier in PK parameter.
my question is,
For every data, after calculating PK parameter is it mandetory to run Lund's test or there is any rules?
please let me know.
Kind Regards,
Yayati
MGR
★    

India,
2008-08-05 07:40
(4639 d 00:19 ago)

@ Yayati
Posting: # 2147
Views: 11,507
 

 Lund's outlier test

Dear Yayati,

Lund's outlier test is used to detect outliers in Pharmacokinetic parameters.

» For every data, after calculating PK parameter is it mandetory to run Lund's test or there is any rules?

It is not mandatory, if you want to detect any outliers from the PK data you have to use this test. Rules means after calculating the residuals you have to see the tabulated value and see whether any outlier is present or not.

May be this helps.

Thank you.

Regards,
MGR
Ravi
★    

India,
2008-08-07 12:40
(4636 d 19:19 ago)

@ MGR
Posting: # 2158
Views: 11,180
 

 Lund's outlier test

Dear MGR,

» Lund's outlier test is used to detect outliers in Pharmacokinetic parameters.
» if you want to detect any outliers from the PK data you have to use this test.

I don't have much knowledge about Lund's outlier test. Could you Please explain it in detail and if possible please suggest some reference.

Please also mention the software on which this test can be performed with some example.

Thanks and Regards
Ravi Pandey

Thanks & Regards
Ravi Pandey
Helmut
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Vienna, Austria,
2008-08-07 15:37
(4636 d 16:22 ago)

@ Ravi
Posting: # 2159
Views: 12,647
 

 Lund's outlier test

Dear Ravi!

» I don't have much knowledge about Lund's outlier test. Could you Please explain it in detail and if possible please suggest some reference.

This test was stated in a guideline issued by the FDA in 1992 (Section V. Outlier Consideration), and dropped in later editions. The original reference is:

Lund RE. Tables for An Approximate Test for Outliers in Linear Models. Technometrics. 1975; 17(4), 473–76.


» Please also mention the software on which this test can be performed with some example.

As a starter you need to calculate studentized intra-subject residuals. WinNonlin and Kinetica cannot, SAS and R can… ;-)
But I would not suggest it anyhow.
Quoting Chow and Liu (2000, pp 501–2) from their critical discussion of FDA’s guideline:

“The guidance provides a pharmacokinetic definition of subject outliers and provides possible causes for their occurrence. The guidance suggests that Lund's method (Lund, 1975) be used for oulier detection. Although Lund’s method is useful in a linear regression setting that requires statistical independence of all PK responses, this method may not be appropriate for a crossover design in which the PK responses from the same subject are correlated. Although Lund's method may be applied to the difference of the PK responses between the test and the reference formulations from the same subject in a standard two-sequence, two-period crossover design, it dose not not take into account the feature of the study design. Moreover, it does not not eliminate other nuisance effects; hence, it cannot be applied to other crossover designs.”


A remark: Chow and Liu are right in their statement of missing independence of observations; on the other hand it does not make sense to apply any outlier test on the raw T/R ratios, but only to the residual errors of the statistical model.
Useful exploratory analyses are box-plots, QQ-plots, Hotelling’s T2, or Cook’s distance.

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shri
☆    

2008-08-22 07:15
(4622 d 00:44 ago)

@ Helmut
Posting: # 2225
Views: 11,246
 

 Lund's outlier test

Dear HS,
How to calculate Lunds outlier manually? which statistic should we use. please explain? i want basic knowledge about it?
thanks in advance. :-)

shri
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