[R] Predicting X from Y in four-parameter fit (SSfpl)

From: Klaus Jensen <KSA_at_ssi.dk>
Date: Fri 09 Jul 2004 - 00:08:48 EST


While analyzing titration-data using four parameter fit, I need to predict single values from the model: I need to predict both ways (ie: X->Y & Y->X):

Example:

library(nls)
cramp<-c(33,100,300,900,2700,8100,24300,72900) myo<-c(2.7130,2.6790,1.5255,0.7675,0.3670,0.2150,0.1575,0.1400) titration<-data.frame(cramp,myo)
nls(myo~SSfpl(log(cramp),A,B,xmid,scal),data=titration) SSfpl(log(2000), coef(sm)[1],coef(sm)[2],coef(sm)[3],coef(sm)[4])

-> [1] 1.060424

This is an example of predicting single values X->Y

Here is my question:
How do I predict the other way around Y->X ??

Any help is appreciated

Best regards,
Klaus
State Serum Institute, Copenhagen



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https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 09 00:16:57 2004

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