AER (version 0.2-2)

ShipAccidents: Ship Accidents

Description

Data on ship accidents.

Usage

data("ShipAccidents")

source

Online complements to Greene (2003). http://pages.stern.nyu.edu/~wgreene/Text/tables/tablelist5.htm

Details

The data are from McCullagh and Nelder (1989, p. 205, Table 6.2) and were also used by Greene (2003, Ch. 21), see below. There are five ships (observations 7, 15, 23, 31, 39) with an operation period before the construction period, hence the variables service and incidents are necessarily 0. An additional observation (34) has entries representing accidentally empty cells (see McCullagh and Nelder, 1989, p. 205). It is a bit unclear what exactly the above means. In any case, the models are fit only to those observations with service > 0.

References

Greene, W.H. (2003). Econometric Analysis, 5th edition. Upper Saddle River, NJ: Prentice Hall. McCullagh, P. and Nelder, J.A. (1989). Generalized Linear Models, 2nd edition. London: Chapman & Hall.

See Also

Greene2003

Examples

data("ShipAccidents")
sa <- subset(ShipAccidents, service > 0)

## Greene (2003), Table 21.20
## (see also McCullagh and Nelder, 1989, Table 6.3)
sa_full <- glm(incidents ~ type + construction + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_full)

sa_notype <- glm(incidents ~ construction + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_notype)

sa_noperiod <- glm(incidents ~ type + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_noperiod)

## model comparison
anova(sa_full, sa_notype, test = "Chisq")
anova(sa_full, sa_noperiod, test = "Chisq")

## test for overdispersion
dispersiontest(sa_full)
dispersiontest(sa_full, trafo = 2)