- On 31 Aug 2006 at 16:53:02, Xiaodong Shen (shenxiaodong11.-a-.yahoo.com) sent the message

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Does anybody know how to using excel to do linear

calibration with a weighing factor 1/x or 1/x^2?

Thanks

Xiaodong - On 1 Sep 2006 at 08:55:00, "Elassaiss - Schaap, J. (Jeroen)" (jeroen.elassaiss.-at-.organon.com) sent the message

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Dear Xiadoing,

In excel you just can calculate the sum of squares yourself and use the

solver for optimization. Then it is just a matter of dividing the

residuals by x^2 before squaring. (Prof. Derendorf showed me this trick

to get PK fits in excel) But be aware that Excel's solver is not optimal

for PK(-PD) problems.

Best regards,

Jeroen

J. Elassaiss-Schaap

Scientist PK/PD

Organon NV

PO Box 20, 5340 BH Oss, Netherlands

Phone: + 31 412 66 9320

Fax: + 31 412 66 2506

e-mail: jeroen.elassaiss.at.organon.com

[At one point Solver was an optionally installed 'add-in' so you may

need to revisit your installation disks to set it up. I found it in

the Tools menu of the Mac version - db] - On 1 Sep 2006 at 10:19:14, "Kris Baert" (kris.baert.aaa.ugent.be) sent the message

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Hello Xiaodong,

The most elegant way is by using the matrix calculation functions in

excel.

The X matrix has two columns with 1 in the first column and the x

values in

the second. The Y matrix has one column with the y values. The weight

matrix

is a diagonal matrix with the 1/x or 1/x2 values. Then use this

formula to

calculate b and a (final matrix is one column, two rows). Don't

forget to

use array formula's.

=MMULT((MINVERSE(MMULT(TRANSPOSE(X);MMULT(W;X))));MMULT(TRANSPOSE

(X);MMULT(W;Y)))

Best regards,

Kris

--

Kris Baert, DVM, PhD

Pharmacology, Toxicology, Biochemistry and Organ Physiology

Veterinary Medicine - Ghent University - On 1 Sep 2006 at 13:08:15, "Porzio, Stefano" (Stefano.Porzio.aaa.ZambonGroup.com) sent the message

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Dear Xiaodong,

you can use, with prudence, the Excel "SOLVER" tool.

An example of spreadsheets setup and calculations for nonlinear

regression (obviously applicable to linear regression problems too)

has been described in TiPS more than 10 years ago by Bowen and Jerman:

Bowen WP, Jerman JC. Nonlinear regression using spreadsheets. Trends

Pharmacol Sci. 1995 Dec;16(12):413-7.

Best regards

Stefano

Dr. Stefano Porzio

Inpharzam Ricerche S.A. ZambonGroup

Taverne

Switzerland - On 1 Sep 2006 at 08:46:32, Mondelo Nelida (nmondelo.aaa.gador.com.ar) sent the message

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You could design your own spreadsheets employing Excel, taking into

account

the following references:

Statistics for analytical chemistry, J.C Millar and Jn Millar or

Selecting the best curve fit, LC.GC Europe, 17 (3), 138-143,2004 Linear

regression for calibration lines revisited: weighing schemes for

bioanalytical methods, J. Chromatography B 774, 215-222,2002.

Hoping to be of help

Valeria Pongelli - On 1 Sep 2006 at 11:48:17, "David S. Farrrier" (DFarrier.at.SummitPK.com) sent the message

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Xiaodong,

PK Solutions is an Excel-based pharmacokinetics data analysis program

that makes PK analysis easy.

The demo copy of PK Solutions illustrates the setup of a nonlinear

regression analysis using the Solver add-in. To see this, download

the demo from www.SummitPK.com/pksolutions/pksolutions.htm (pre and

post Excel XP versions are available). Open the workbook to the

"Curve Fit" spreadsheet tab. Click the "Curve Fitting Procedure"

button for an explanation of how this works. Note that the demo

illustrates the software in detail, but is disabled from performing

personal data sets.

Regards,

David

/\ /\

SummitPK.com /\ / \ /\ / \

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=================================================

David S. Farrier, Ph.D. Phone: 970-249-1389

Summit Research Services Fax: 970-249-1360

68911 Open Field Dr. Email: DFarrier.-a-.SummitPK.com

Montrose, CO 81401 Web: http://www.SummitPK.com

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