On this R-data statistics page, you will find information about the anesthetic data set which pertains to Anesthetic Effectiveness. The anesthetic data set is found in the DAAG R package. You can load the anesthetic data set in R by issuing the following command at the console data("anesthetic"). This will load the data into a variable called anesthetic. If R says the anesthetic data set is not found, you can try installing the package by issuing this command install.packages("DAAG") and then attempt to reload the data. If you need to download R, you can go to the R project website. You can download a CSV (comma separated values) version of the anesthetic R data set. The size of this file is about 723 bytes.
Thirty patients were given an anesthetic agent maintained at a predetermined level (conc) for 15 minutes before making an incision. It was then noted whether the patient moved, i.e. jerked or twisted.
This data frame contains the following columns:
a binary numeric vector coded for patient movement (0 = no movement, 1 = movement)
logarithm of concentration
the complement of move
The interest is in estimating how the probability of jerking or twisting varies with increasing concentration of the anesthetic agent.
print("Logistic Regression - Example 8.1.4")z <- table(anesthetic$nomove, anesthetic$conc)
tot <- apply(z, 2, sum) # totals at each concentration
prop <- z[2, ]/(tot) # proportions at each concentration
oprop <- sum(z[2, ])/sum(tot) # expected proportion moving if concentration had no effect
conc <- as.numeric(dimnames(z)[])
plot(conc, prop, xlab = "Concentration", ylab = "Proportion", xlim = c(.5,2.5),
ylim = c(0, 1), pch = 16)
chw <- par()$cxy
text(conc - 0.75 * chw, prop, paste(tot), adj = 1)
abline(h = oprop, lty = 2)pause()anes.logit <- glm(nomove ~ conc, family = binomial(link = logit),
data = anesthetic)
Dataset imported from https://www.r-project.org.