anesthetic {DAAG} | R Documentation |
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.
anesthetic
This data frame contains the following columns:
The interest is in estimating how the probability of jerking or twisting varies with increasing concentration of the anesthetic agent.
unknown
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)[[2]]) plot(conc, prop, xlab = "Concentration", ylab = "Proportion", xlim = c(.5,2.5), ylim = c(0, 1), pch = 16) chw <- par()$cxy[1] 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) anova(anes.logit) summary(anes.logit)