loomis

Description

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.

Usage

data(loomis)

Format

A data frame with 410 observations on the following 11 variables.

anvisits

number of annual visits to park

gender

1=male;0=female

income

income in US dollars per year, categorical: 4 levels

income1

<=$25000

income2

>$25000 - $55000

income3

>$55000 - $95000

income4

>$95000

travel

travel time, categorical: 3 levels

travel1

<.25 hrs

travel2

>=.25 - <4 hrs

travel3

>=4 hrs

Details

loomis is saved as a data frame. Count models typically use anvisits as response variable. 0 counts are included

Source

from Loomis (2003)

References

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

Examples

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))