lizards: Habitat Preference of Lizards

Description

This data set describes the habitat preference of two species of lizards, Anolis grahami and A. opalinus, on the island of Jamaica and is originally from Schoener (1970). McCullagh and Nelder (1989) and Burnham and Anderson (2002) reanalyzed the data. Note that a typo occurs in table 3.11 of Burnham and Anderson (2002).

Usage

data(lizards)

Arguments

Format

A data frame with 48 rows and 6 variables.

Insolation: position of perch, either shaded or sunny.
Diameter: diameter of the perch, either < 2 in or >= 2 in.
Height: perch height, either < 5 or >= 5.
Time: time of day, either morning, midday, or afternoon.
Species: species observed, either grahami or opalinus.
Counts: number of individuals observed.

Details

Burnham and Anderson (2002, p. 137) use this data set originally from Schoener (1970) to illustrate model selection for log-linear models.

Examples

Run this code

# NOT RUN {
data(lizards)
# }
# NOT RUN {
##log-linear model as in Burnham and Anderson 2002, p. 137
##main effects
m1 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species, 
          family = poisson, data = lizards)


##main effects and all second order interactions = base
m2 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Time +
          Diameter:Species + Height:Time + Height:Species +
          Time:Species, family = poisson, data = lizards)

##base - DT
m3 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Species +
          Height:Time + Height:Species + Time:Species, 
          family = poisson, data = lizards)

##base + HDI + HDT + HDS
m4 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Time +
          Diameter:Species + Height:Time + Height:Species +
          Time:Species + Height:Diameter:Insolation +
          Height:Diameter:Time + Height:Diameter:Species, 
          family = poisson, data = lizards)

##base + HDI + HDS + HIT + HIS + HTS + ITS
m5 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species + 
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Time +
          Diameter:Species + Height:Time + Height:Species +
          Time:Species + Height:Diameter:Insolation +
          Height:Diameter:Species + Height:Insolation:Time +
          Height:Insolation:Species + Height:Time:Species +
          Insolation:Time:Species, family = poisson, data = lizards)

##base + HIT + HIS + HTS + ITS
m6 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species + 
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Time +
          Diameter:Species + Height:Time + Height:Species +
          Time:Species + Height:Insolation:Time +
          Height:Insolation:Species +  Height:Time:Species +
          Insolation:Time:Species,  family = poisson, data = lizards)

##base + HIS + HTS + ITS
m7 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Time +
          Diameter:Species + Height:Time + Height:Species +
          Time:Species + Height:Insolation:Species +
          Height:Time:Species + Insolation:Time:Species, 
          family = poisson, data = lizards)

##base + HIT + HIS + HTS + ITS - DT
m8 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Species +
          Height:Time + Height:Species + Time:Species +
          Height:Insolation:Time + Height:Insolation:Species +
          Height:Time:Species + Insolation:Time:Species, 
          family = poisson, data = lizards)

##base + HIT + HIS + ITS - DT
m9 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Species +
          Height:Time + Height:Species + Time:Species +
          Height:Insolation:Time + Height:Insolation:Species +
          Insolation:Time:Species, 
          family = poisson, data = lizards)

##base + HIT + HIS - DT
m10 <- glm(Counts ~ Insolation + Diameter + Height + Time + Species +
          Insolation:Diameter + Insolation:Height + Insolation:Time +
          Insolation:Species + Diameter:Height + Diameter:Species +
          Height:Time + Height:Species + Time:Species +
          Height:Insolation:Time + Height:Insolation:Species,
          family = poisson, data = lizards)

##set up in list
Cands <- list(m1, m2, m3, m4, m5, m6, m7, m8, m9, m10)
Modnames <- paste("m", 1:length(Cands), sep = "")

##model selection
library(AICcmodavg)
aictab(Cands, Modnames)
# }