DNase                package:datasets                R Documentation

_E_l_i_s_a _a_s_s_a_y _o_f _D_N_a_s_e

_D_e_s_c_r_i_p_t_i_o_n:

     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.

_U_s_a_g_e:

     DNase

_F_o_r_m_a_t:

     This data frame contains the following columns:

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

     _c_o_n_c a numeric vector giving the known concentration of the
          protein. 

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

_S_o_u_r_c_e:

     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.

_E_x_a_m_p_l_e_s:

     require(stats)
     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)

