Dear
I investigated herbicide affect on weeds growth (dose-response). I used drc
package and fitted data to best model by mselect function and parameters of
models. For some data, Logistic model was the best and for others, Weibull.
But when I wanted to draw relative potency curve, the R-program displayed
error massage just for Weibull model (attachment files).
could you please help me?
thanks a lot.
your sincerely, Ahmad Rahbari
> mydata<- read.csv ("D:\\MY Data\\R\\Tri-set.csv" , sep=",", dec=".",
> header=TRUE)
> mydata1 <- drm (Survival ~ Dose, Herbicide, fct = W1.3(), data=mydata)
> summary(mydata1)
Model fitted: Weibull (type 1) with lower limit at 0 (3 parms)
Parameter estimates:
Estimate Std. Error t-value p-value
b:EC 1.440454 0.239782 6.0073 3.346e-06 ***
b:MC 1.915474 0.320034 5.9852 3.533e-06 ***
d:EC 100.489083 5.303133 18.9490 6.368e-16 ***
d:MC 100.356215 5.257064 19.0898 4.791e-16 ***
e:EC 0.711835 0.054866 12.9740 2.444e-12 ***
e:MC 0.637447 0.042248 15.0882 9.551e-14 ***
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error:
9.398498 (24 degrees of freedom)
> EDcomp(mydata1, c(10,10), interval = "delta")
Estimated ratios of effect doses
Estimate Lower Upper
EC/MC:10/10 0.75802 0.18863 1.32740
> EDcomp(mydata1, c(50,50), interval = "delta")
Estimated ratios of effect doses
Estimate Lower Upper
EC/MC:50/50 1.04841 0.77686 1.31997
> EDcomp(mydata1, c(90,90), interval = "delta")
Estimated ratios of effect doses
Estimate Lower Upper
EC/MC:90/90 1.2891 0.9224 1.6559
> relpot(mydata1, plotit = TRUE, compMatch = NULL, percVec = NULL, interval =
> "none", type="relative")
Error in match.fun(FUN) :
'object$fct$lowerAs' is not a function, character or symbol
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