Description Usage Arguments Details Value References See Also Examples
Assess the fit of a doseresponse curve using the chisquared statistic. The curve is described by the intercept and slope of a straight line in the log dose vs. probit effect scale.
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params 
A numeric vector of length two, with the estimated intercept and slope of the doseeffect relation on the log10 and probit scale. These parameters define the doseresponse curve. 
DEdata 
A data frame of doseeffect data (typically, the output from

fit 
A model object that can be used to predict the corrected values
(as proportions) from 
simple 
A logical scalar indicating if the output should be restricted to just the P value, default TRUE. 
This function is used to find the doseresponse curve that minimizes the
chisquared statistic measuring the distance between the observed and
expected values of the response (the proportion affected).
Following Litchfield and Wilcoxon (1949, steps B1 and B2),
records with expected effects < 0.01% or > 99.99% are deleted, and
other expected effects are "corrected" using the
correctval
function.
If simple=FALSE
, a list of length two. The first element,
chi
, is a numeric vector of length three:
chistat
, chisquared statistic;
df
, degrees of freedom; and
pval
, P value.
The second element,
contrib
, is a matrix of three numeric vectors the same length as
obsn
:
exp
, expected effects;
obscorr
, observed effects corrected; and
contrib
, contributions to the chisquared.
If simple=TRUE
, a numeric scalar, the chisquared statistic
(see details).
Litchfield, JT Jr. and F Wilcoxon. 1949. A simplified method of evaluating doseeffect experiments. Journal of Pharmacology and Experimental Therapeutics 96(2):99113. [link].
LWchi2
and chisq.test
.
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