lizards {AICcmodavg}

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)

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.

Source

Burnham, K. P., Anderson, D. R. (2002) Model Selection and Multimodel Inference: a practical information-theoretic approach. Second edition. Springer: New York.

McCullagh, P., Nelder, J. A. (1989) Generalized Linear Models. Second edition. Chapman and Hall: New York.

Schoener, T. W. (1970) Nonsynchronous spatial overlap of lizards in patchy habitats. Ecology 51, 408–418.

Examples

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)

## End(Not run)