DNase                  package:nls                  R Documentation

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:

     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)

