I have uploaded a datafile that contains the following two variables: time
(X value) and response (Y value). This is a fairly extensive file (with >
16000 entries). I have two questions:
1. I want to use the following equation to regress Y on X: Y-hat = min +
(max-min)/(1 + (X/EC50)^Hillslope).
Here is my R command:
nlsout <- nls(Y ~ (0 - (100-0)/(1 + (X/EC50)^hill)), start=c(EC50=125,
hill=-1))
However, I get the following error message:
Error in numericDeriv(form[[3L]], names(ind), env) :
Missing value or an infinity produced when evaluating the model
Could someone explain the error message to me, please, and what I need to do
to be able to run the command without error? The problem is that this exact
same formula works on the exact same dataset when I use a macro in Excel
(unfortunately I don't have the code, though).
2. I want to compute the prediction band for the above regression.
Any help will be greatly appreciated.
Thanks,
Joe
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