moths: Moths Data

In jhmaindonald/DAAG: Data Analysis and Graphics Data and Functions

Description

The moths data frame has 41 rows and 4 columns. These data are from a study of the effect of habitat on the densities of two species of moth (A and P). Transects were set across the search area. Within transects, sections were identified according to habitat type.

Usage

moths

Format

This data frame contains the following columns:

meters

length of transect

A

number of type A moths found

P

number of type P moths found

habitat

a factor with levels Bank, Disturbed, Lowerside, NEsoak, NWsoak, SEsoak, SWsoak, Upperside

Source

Sharyn Wragg, formerly of Australian National University

Examples

print("Quasi Poisson Regression - Example 8.3")
rbind(table(moths[,4]), sapply(split(moths[,-4], moths$habitat), apply,2,
sum))
A.glm <- glm(formula = A ~ log(meters) + factor(habitat), family =
quasipoisson, data = moths)
summary(A.glm)
  # Note the huge standard errors
moths$habitat <- relevel(moths$habitat, ref="Lowerside")
A.glm <- glm(A ~ habitat + log(meters), family=quasipoisson, data=moths)
summary(A.glm)$coef
## Consider as another possibility
A2.glm <- glm(formula = A ~ sqrt(meters) + factor(habitat), family =
                  quasipoisson(link=sqrt), data = moths)
summary(A2.glm)

jhmaindonald/DAAG documentation built on May 3, 2019, 3:13 p.m.