Assay                  package:nlme                  R Documentation

Bioassay on Cell Culture Plate

Description:

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

Format:

     This data frame contains the following columns:

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

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

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

     logDens a numeric vector of the log-optical density


Details:

     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.

Source:

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

