UKDriverDeaths
is a time series giving the monthly totals
of car drivers in
Great Britain killed or seriously injured Jan 1969 to Dec 1984.
Compulsory wearing of seat belts was introduced on 31 Jan 1983. Seatbelts
is more information on the same problem.
UKDriverDeaths
Seatbelts
Seatbelts
is a multiple time series, with columns
DriversKilled
drivers
UKDriverDeaths
.front
rear
kms
PetrolPrice
VanKilled
law
require(stats); require(graphics)
## work with pre-seatbelt period to identify a model, use logs
work <- window(log10(UKDriverDeaths), end = 1982+11/12)
par(mfrow = c(3, 1))
plot(work); acf(work); pacf(work)
par(mfrow = c(1, 1))
(fit <- arima(work, c(1, 0, 0), seasonal = list(order = c(1, 0, 0))))
z <- predict(fit, n.ahead = 24)
ts.plot(log10(UKDriverDeaths), z$pred, z$pred+2*z$se, z$pred-2*z$se,
lty = c(1, 3, 2, 2), col = c("black", "red", "blue", "blue"))
## now see the effect of the explanatory variables
X <- Seatbelts[, c("kms", "PetrolPrice", "law")]
X[, 1] <- log10(X[, 1]) - 4
arima(log10(Seatbelts[, "drivers"]), c(1, 0, 0),
seasonal = list(order = c(1, 0, 0)), xreg = X)
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