An Automated Approach to Evaluating Dose-Effect Experiments Following Litchfield and Wilcoxon (1949)

The manual approach of Litchfield and Wilcoxon (1949) <> for evaluating dose-effect experiments is automated so that the computer can do the work.


LW1949 1.1.0

  • Constrained corrected values for observed effects of 0% to a maximum of 10.5% and those for observed effects of 100% to a minimum of 89.5% in keeping with the intended application of Litchfield and Wilcoxon's (1949) Table 1.
  • Incorporated rounding in keeping with the true approach taken by Litchfield and Wilcoxon (1949)
    • fitlinear() - default setting for argument constr set to c(0.0005, 0.9995).
    • assessfit() - exclude records with expected effects < 0.005% or > 99.995%.
    • correctval() - apply corrected values to expected effects < 0.5% or > 99.5%.
    • LWestimate() - calculate Nprime as number of observations between ED15.5% and ED84.5%.
  • Introduced greater flexibility in plotting functions.
    • plotDELP() - added argument grid.
    • LWnomo1() - added argument ....
  • Extended predLines() and predLinesLP() to cover entire x-range.
  • Added citation (Adams et al. 2016).

LW1949 1.0.0

  • Package first submitted to CRAN

Reference manual

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1.1.0 by Jean V. Adams, a year ago

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Browse source code at

Authors: Jean V. Adams [aut, cre]

Documentation:   PDF Manual  

GPL license

Imports MASS, mgcv, plotrix, tcltk, grDevices, graphics, stats, utils

Suggests magrittr, testthat, knitr, rmarkdown

See at CRAN