piepho.cocksfoot {agridat}R Documentation

Heading dates for cock's foot on 25 varieties in 7 years

Description

Heading dates for cock's foot on 25 varieties in 7 years

Usage

data("piepho.cocksfoot")

Format

A data frame with 111 observations on the following 3 variables.

gen

genotype factor, 25 levels

year

year, numeric

date

heading date (days from April 1)

Details

These data are heading dates (days from April 1 to heading) of 25 cock's foot Dactylis glomerata varieties in trials at Hannover, Germany, repeated over seven years. Values are means over replications.

Source

Hans-Pieter Piepho. (1999). Fitting a Regression Model for Genotype-by-Environment Data on Heading Dates in Grasses by Methods for Nonlinear Mixed Models. Biometrics, 55, 1120-1128. http://doi.org/10.1111/j.0006-341X.1999.01120.x

Examples


data(piepho.cocksfoot)
dat <- piepho.cocksfoot
dat$env <- factor(dat$year)

require(lattice)
densityplot(~date|env, data=dat, main="piepho.cocksfoot - heading date") # Gaussian, not gamma distn

## Not run: 
  require(lme4)
  # A simple mixed model gives results similar to Piepho, Table 2.
  m1 <- lmer(date ~ -1 + gen + (1|env), data=dat)
  summary(m1)
  ## Fixed effects:
  ##        Estimate Std. Error t value
  ## genG01   48.951      1.744   28.07
  ## genG02   42.270      1.755   24.09
  ## genG03   45.293      1.744   25.98
  ## genG04   45.467      1.744   26.08
  ## genG05   44.215      1.755   25.20

## End(Not run)


[Package agridat version 1.16 Index]