Hepaga {mffSM}R Documentation

PK/PD data from hematology

Description

Pharmacokinetics/pharmacodynamics data from hematology useful for excercises in non-linear regression.

The relationship between the response Y and the explanatory variable x might be modelled as

EY = -log(a) + log(log(1 + x/b)),

where a and b are unknown parameters.

Usage

data(Hepaga)

Format

A data.frame with 12 rows and the following variables.

x

explanatory variable

y

response

Examples

data(Hepaga)
summary(Hepaga)

### Plot data
plot(y~x, col="red3", bg="orange", pch=22, data=Hepaga)

### Non-linear regression
rfce1 <- deriv3(~-log(a) + log(log(1+x/b)), 
               namevec=c("a", "b"), 
               function.arg=function(x, a, b){})
m1 <- nls(y~rfce1(x, a, b), start=list(a=1, b=1), data=Hepaga)
summary(m1)

### Estimated regression function
xx <- data.frame(x=seq(min(Hepaga$x), max(Hepaga$x), length=50))
pm1 <- predict(m1, xx)
plot(y~x, col="red3", bg="orange", pch=22, data=Hepaga)
lines(xx$x, pm1, col="red4", lwd=2)

### Alternative parametrization
rfce2 <- deriv3(~-log(a) + log(log(1 + a*x/e)),
                namevec=c("a", "e"), 
                function.arg=function(x, a, e){})
m2 <- nls(y~rfce2(x, a, e), start=list(a=1, e=1), data=Hepaga)
summary(m2)

[Package mffSM version 1.2 Index]