Hi Greg,
you can use the extension package 'drc' from CRAN:
conc <- c(10.3, 10.8, 11.6, 13.2, 15.8, 20.1) # Exposure concentrations
orign <- c(76, 79, 77, 76, 78, 77) # Original number of subjects
ndead <- c(16, 22, 40, 69, 78, 77) # Number dead after 96 h
d <- data.frame(conc=conc, orign=orign
I am attempting to estimate LC50 (analogous to LD50, but uses exposure
concentration rather than dose) by fitting a Weibull model; but I
can't seem to get it to work. From what I can gather, I should be
using survreg() from the survival package. The survreg() function
relies on time-to-event data
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