becker.chicken: Mating crosses of chickens

Description Usage Format Details Source References Examples

Description

Mating crosses of chickens

Usage

1
data("becker.chicken")

Format

A data frame with 45 observations on the following 3 variables.

male

male parent

female

female parent

weight

weight (g) at 8 weeks

Details

From a large flock White Rock chickens, five male sires were chosen and mated to each of three female dams, producing 3 female progeny. The data are body weights at eight weeks of age.

Becker (1984) used these data to demonstrate the calculation of heritability.

Source

Walter A. Becker (1984). Manual of Quantitative Genetics, 4th ed. Page 83.

References

None

Examples

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data(becker.chicken)
dat <- becker.chicken

if(require(lattice)){
  dotplot(weight ~ female, data=dat, group=male,
          main="becker.chicken - progeny weight by M*F",
          xlab="female parent",ylab="progeny weight",
          auto.key=list(columns=5))
}

## Not run: 
  # Sums match Becker
  sum(dat$weight)
  aggregate(weight ~  male + female, dat, FUN=sum)

  # Variance components
  require(lme4)
  require(lucid)
  m1 <- lmer(weight ~  (1|male) + (1|female), data=dat)
  as.data.frame(lme4::VarCorr(m1))
  ## grp        var1 var2      vcov    sdcor
  ## 1   female (Intercept) <NA> 1095.6296 33.10030
  ## 2     male (Intercept) <NA>  776.7543 27.87031
  ## 3 Residual        <NA> <NA> 5524.4000 74.32631

  # Calculate heritabilities
  s2m <- 776  # variability for males
  s2f <- 1095 # variability for females
  s2w <- 5524 # variability within crosses
  vp <- s2m + s2f + s2w # 7395
  4*s2m/vp # .42 male heritability
  4*s2f/vp # .59 female heritability


## End(Not run)

agridat documentation built on May 2, 2019, 4:01 p.m.