R: Elisa assay of DNase

DNase {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)

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