optima in unimode

Dear all
i could not estimate the optima value or range value in unimodal plot in glm
please help me out

thanking you 

regard
madan

You're going to have to give us more to go on than that, but...

Are you an ecologist and you want to estimate the optima and tolerance
range from a fitted logit model? If so, here is an example:

## install.packages("analogue") if not installed
require(analogue)
data(ImbrieKipp, SumSST)

## fit a model
mod <- glm(G.pacR ~ SumSST + I(SumSST^2), data = ImbrieKipp/100,
           family = binomial)
## plot it
pdat <- data.frame(SumSST= seq(min(SumSST), max(SumSST), length = 100))
p2 <- predict(mod, pdat, type = "response")
lines(p2 ~ SumSST, data = pdat, col = "blue", lwd = 3)

## model ceofficients
c.mod <- coef(mod)
## optima
-c.mod[2]/(2 * c.mod[3])
## tolerance
sqrt(-(1/(2 * c.mod[3])))
## height == abundance at optimum
exp(c.mod[1] - (c.mod[2]^2/(4 * c.mod[3])))

HTH

G

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