grouseticks

0th

Percentile

Number of ticks on the heads of red grouse chicks sampled in the field (grouseticks) and an aggregated version (grouseticks_agg); see original source for more details

Keywords
datasets
Usage
data(grouseticks)
Details

grouseticks_agg is just a brood-level aggregation of the data

Format

INDEX
(factor) chick number (observation level)
TICKS
number of ticks sampled
BROOD
(factor) brood number
HEIGHT
height above sea level (meters)
YEAR
year (-1900)
LOCATION
(factor) geographic location code
cHEIGHT
centered height, derived from HEIGHT
meanTICKS
mean number of ticks by brood
varTICKS
variance of number of ticks by brood

References

Elston, D. A., R. Moss, T. Boulinier, C. Arrowsmith, and X. Lambin. 2001. "Analysis of Aggregation, a Worked Example: Numbers of Ticks on Red Grouse Chicks." Parasitology 122 (05): 563-569. doi:10.1017/S0031182001007740. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=82701.

Aliases
  • grouseticks
  • grouseticks_agg
Examples
data(grouseticks)
## Figure 1a from Elston et al
par(las=1,bty="l")
tvec <- c(0,1,2,5,20,40,80)
pvec <- c(4,1,3)
with(grouseticks_agg,plot(1+meanTICKS~HEIGHT,
                  pch=pvec[factor(YEAR)],
                  log="y",axes=FALSE,
                  xlab="Altitude (m)",
                  ylab="Brood mean ticks"))
axis(side=1)
axis(side=2,at=tvec+1,label=tvec)
box()
abline(v=405,lty=2)
## Figure 1b
with(grouseticks_agg,plot(varTICKS~meanTICKS,
                  pch=4,
                  xlab="Brood mean ticks",
                  ylab="Within-brood variance"))
curve(1*x,from=0,to=70,add=TRUE)
## Model fitting
form <- TICKS~YEAR+HEIGHT+(1|BROOD)+(1|INDEX)+(1|LOCATION)
(full_mod1  <- glmer(form, family="poisson",data=grouseticks))
Documentation reproduced from package lme4, version 1.1-13, License: GPL (>= 2)

Community examples

Looks like there are no examples yet.