compParm {drc} | R Documentation |
Compare parameters from different assays, either by means of ratios or differences.
compParm(object, strVal, operator = "/", od = FALSE)
object |
an object of class 'drc'. |
strVal |
a name of parameter to compare. |
operator |
a character. If equal to "/" (default) parameter ratios are compared. If equal to "-" parameter differences are compared. |
od |
logical. If TRUE adjustment for over-dispersion is used. |
The function compares actual parameter estimates, and therefore the results depend on the parameterisation used. Probably it is most useful
in combination with 'collapse' arguments (in drm
) that are data frames or lists with formulas without intercept (-1).
A matrix with columns containing the estimates, estimated standard errors, values of t-statistics and p-values for the null hypothesis that
the ratio equals 1 or that the difference equals 0 (depending on the operator
argument).
No adjustment for multiplicity is applied. See p.adjust
on how to do adjust p-values.
Christian Ritz
# Fitting a model with names assigned to the parameters! spinach.m1 <- drm(SLOPE~DOSE, CURVE, data = spinach, fct = LL.4(names = c("b", "lower", "upper", "ed50"))) ## Calculating ratios of parameter estimates for the parameter named "ed50" compParm(spinach.m1, "ed50") ## Calculating differences between parameter estimates for the parameter named "ed50" compParm(spinach.m1, "ed50", "-")