From: Nick Holford <*n.holford*>

Date: Thu, 05 Nov 2009 16:40:05 +1300

Peiming,

Thank you for pointing out my mistake again!

Perhaps next time you should make the correction and send it to nmusers :-)

MU_1=LOG(THETA(1)/(1-THETA(1)) ; logit of population bioavailability

EXPP=MU_1+ETA(1) ; add random effect

BIO=1/(1+EXP(-EXPP)) ; individual bioavailability

Nick

Ma, Peiming wrote:

*>
*

*> Unfortunately, Nick, you have an extra EXP: the denominator of BIO
*

*> should be just 1 + EXP(-EXPP). J
*

*>
*

*>
*

*>
*

*> Cheers,
*

*>
*

*>
*

*>
*

*> ------------------------------------------------------------------------
*

*>
*

*> *From:* owner-nmusers *

*> [mailto:owner-nmusers *

*> *Sent:* Wednesday, November 04, 2009 3:43 PM
*

*> *To:* nmusers
*

*> *Subject:* Re: [NMusers] advan8 vs. advan13 (CORRECTION)
*

*>
*

*>
*

*>
*

*> Hi,
*

*>
*

*> Thanks to Peiming Ma and Thuy Vu for pointing out an error in my
*

*> attempt to transform bioavailability into its logit.
*

*>
*

*> The logit transformation of a probability is ln(P/(1-P)) i.e. the log
*

*> of the odds ratio. The reverse transform is correct i.e. exp(logit) is
*

*> the odds ratio and P is then OR/(1+OR) (or 1/1+exp(-logit)).
*

*>
*

*> If THETA(1) is the bioavailability then this is (I hope) the correct
*

*> transformation of THETA(1) and reverse transform to get the
*

*> individual bioavailability with a random effect constrained to be
*

*> within 0 and 1.
*

*>
*

*> MU_1=LOG(THETA(1)/(1-THETA(1)) ; logit of population bioavailability
*

*>
*

*> EXPP=MU_1+ETA(1) ; add random effect
*

*>
*

*> BIO=1/(1+EXP(-EXP(EXPP))) ; individual bioavailability
*

*>
*

*>
*

*> Nick
*

*>
*

*> --
*

*> Nick Holford, Professor Clinical Pharmacology
*

*> Dept Pharmacology & Clinical Pharmacology
*

*> University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
*

*> tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53
*

*> email: n.holford *

*> http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford
*

--

Nick Holford, Professor Clinical Pharmacology

Dept Pharmacology & Clinical Pharmacology

University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand

tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53

email: n.holford

http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford

Received on Wed Nov 04 2009 - 22:40:05 EST

Date: Thu, 05 Nov 2009 16:40:05 +1300

Peiming,

Thank you for pointing out my mistake again!

Perhaps next time you should make the correction and send it to nmusers :-)

MU_1=LOG(THETA(1)/(1-THETA(1)) ; logit of population bioavailability

EXPP=MU_1+ETA(1) ; add random effect

BIO=1/(1+EXP(-EXPP)) ; individual bioavailability

Nick

Ma, Peiming wrote:

--

Nick Holford, Professor Clinical Pharmacology

Dept Pharmacology & Clinical Pharmacology

University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand

tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53

email: n.holford

http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford

Received on Wed Nov 04 2009 - 22:40:05 EST