anesthetic | R Documentation |

## Anesthetic Effectiveness

### Description

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.

### Usage

anesthetic

### Format

This data frame contains the following columns:

- move
a binary numeric vector coded for
patient movement (0 = no movement, 1 = movement)

- conc
anesthetic concentration

- logconc
logarithm of concentration

- nomove
the complement of move

### Details

The interest is in estimating
how the probability of jerking or twisting varies with
increasing concentration of the anesthetic agent.

### Source

unknown

### Examples

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)