Elisa assay of DNase

Description

The DNase data frame has 176 rows and 3 columns of data obtained during development of an ELISA assay for the recombinant protein DNase in rat serum.

Format

This data frame contains the following columns:

Run

an ordered factor with levels 10 < ... < 3 indicating the assay run.

conc

a numeric vector giving the known concentration of the protein.

density

a numeric vector giving the measured optical density (dimensionless) in the assay. Duplicate optical density measurements were obtained.

Source

Davidian, M. and Giltinan, D. M. (1995) Nonlinear Models for Repeated Measurement Data, Chapman & Hall (section 5.2.4, p. 134)

Pinheiro, J. C. and Bates, D. M. (2000) Mixed-effects Models in S and S-PLUS, Springer.

Examples

library(nls)
data(DNase)
coplot(density ~ conc | Run, data = DNase,
    show = FALSE, type = "b")
coplot(density ~ log(conc) | Run, data = DNase,
    show = FALSE, type = "b")
## fit a representative run
fm1 <- nls(density ~ SSlogis( log(conc), Asym, xmid, scal ),
    data = DNase, subset = Run == 1)
## compare with a four-parameter logistic
fm2 <- nls(density ~ SSfpl( log(conc), A, B, xmid, scal ),
    data = DNase, subset = Run == 1)
summary(fm2)
anova(fm1, fm2)