Chapter 3 Exercises

3.5.1

Use the read.table function to read in the syphilis. Evaluate structure of data frame. Do not attach the data frame (yet). Create a 3-dimensional array using both the table or xtabs function. Now attach the data frame using the attach function. Create the same 3-dimensional array using both the table or xtabs function.

std <- read.table(“~/git/phds/data/syphilis89c.txt”, head = TRUE, sep = “,”)

str(std)

head(std)

lapply(std, table)

table(std\(Race, std\)Age, std$Sex)

xtabs(~ Race + Age + Sex, data = std)

attach(std)

table(Race, Age, Sex)

xtabs(~ Race + Age + Sex)

detach(std)