Description Usage Arguments Details Value Note Author(s) See Also Examples
Providing the mean function and the corresponding self starter function for the asymptotic regression model.
1 2 3 |
fixed |
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed. |
names |
vector of character strings giving the names of the parameters (should not contain ":"). |
... |
additional arguments to be passed from the convenience functions. |
The asymptotic regression model is a three-parameter model with mean function:
f(x) = c + (d-c)(1-\exp(-x/e))
The parameter c is the lower limit (at x=0), the parameter d is the upper limit and the parameter e>0 is determining the steepness of the increase as x.
A list of class drcMean
, containing the mean function, the self starter function,
the parameter names and other components such as derivatives and a function for calculating ED values.
The functions are for use with the function drm
.
Christian Ritz
A very similar, but monotonously decreasing model is the exponential decay model:
EXD.2
and EXD.3
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | ## First model
met.as.m1<-drm(gain ~ dose, product, data = methionine, fct = AR.3(),
pmodels = list(~1, ~factor(product), ~factor(product)))
plot(met.as.m1, log = "", ylim = c(1450, 1800))
summary(met.as.m1)
## Calculating bioefficacy: approach 1
coef(met.as.m1)[5] / coef(met.as.m1)[4] * 100
## Calculating bioefficacy: approach 2
EDcomp(met.as.m1, c(50,50))
## Simplified models
met.as.m2<-drm(gain ~ dose, product, data = methionine, fct = AR.3(),
pmodels = list(~1, ~1, ~factor(product)))
anova(met.as.m2, met.as.m1) # simplification not possible
met.as.m3 <- drm(gain ~ dose, product, data = methionine, fct = AR.3(),
pmodels = list(~1, ~factor(product), ~1))
anova(met.as.m3, met.as.m1) # simplification not possible
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