# Historical New York measurements, May–September 1973 (bundled with R)
data("airquality", package = "datasets")
dim(airquality)
colSums(is.na(airquality))
cat("Nonmissing ozone days:", sum(!is.na(airquality$Ozone)), "\n")
model <- lm(Ozone ~ Solar.R + Wind + Temp, data = airquality)
cat("Days supplied:", nrow(airquality), "\n")
cat("Complete-case days in model:", nobs(model), "\n")
summary(airquality$Ozone)
plot(airquality$Temp, airquality$Ozone, pch = 19,
     col = "#476E74", xlab = "Daily max temperature (F)",
     ylab = "Ozone (ppb)", main = "1973 New York airquality: observed pairs")