Data are taken from Loomis (2003). The study relates to a survey taken on reported frequency of visits to national parks during the year. The survey was taken at park sites, thus incurring possible effects of endogenous stratification.
A data frame with 410 observations on the following 11 variables.
number of annual visits to park
income in US dollars per year, categorical: 4 levels
>$25000 - $55000
>$55000 - $95000
travel time, categorical: 3 levels
>=.25 - <4 hrs
loomis is saved as a data frame. Count models typically use anvisits as response variable. 0 counts are included
from Loomis (2003)
Hilbe, Joseph M (2007, 2011), Negative Binomial Regression, Cambridge University Press Loomis, J. B. (2003). Travel cost demand model based river recreation benefit estimates with on-site and household surveys: Comparative results and a correction procedure, Water Resources Research, 39(4): 1105
data(loomis) glmlmp <- glm(anvisits ~ gender + factor(income) + factor(travel), family=poisson, data=loomis) summary(glmlmp) exp(coef(glmlmp)) library(MASS) glmlmnb <- glm.nb(anvisits ~ gender + factor(income) + factor(travel), data=loomis) summary(glmlmnb) exp(coef(glmlmnb))