[R] problem in drawing relative potency curve

[Ahmad Rahbari]

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

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