Assay                  package:nlme                  R Documentation

_B_i_o_a_s_s_a_y _o_n _C_e_l_l _C_u_l_t_u_r_e _P_l_a_t_e

_D_e_s_c_r_i_p_t_i_o_n:

     The 'Assay' data frame has 60 rows and 4 columns.

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _B_l_o_c_k an ordered factor with levels '2' < '1' identifying the
          block where the wells are measured.

     _s_a_m_p_l_e a factor with levels 'a' to 'f' identifying the sample
          corresponding to the well.

     _d_i_l_u_t a factor with levels '1' to '5' indicating the dilution
          applied to the well

     _l_o_g_D_e_n_s a numeric vector of the log-optical density


_D_e_t_a_i_l_s:

     These data, courtesy of Rich Wolfe and David Lansky from Searle,
     Inc., come from a bioassay run on a 96-well cell culture plate. 
     The assay is performed using a split-block design.  The 8 rows on
     the plate are labeled A-H from top to bottom and the 12 columns on
     the plate are labeled 1-12 from left to right.  Only the central
     60 wells of the plate are used for the bioassay (the intersection
     of rows B-G and columns 2-11).  There are two blocks in the
     design: Block 1 contains columns 2-6 and Block 2 contains columns
     7-11. Within each block, six samples are assigned randomly to rows
     and five (serial) dilutions are assigned randomly to columns. The
     response variable is the logarithm of the optical density. The
     cells are treated with a compound that they metabolize to produce
     the stain.  Only live cells can make the stain, so the optical
     density is a measure of the number of cells that are alive and
     healthy.

_S_o_u_r_c_e:

     Pinheiro, J. C. and Bates, D. M. (2000), _Mixed-Effects Models in
     S and S-PLUS_, Springer, New York. (Appendix A.2)