\name{Geissler}
\alias{Geissler}
\docType{data}

\title{Geissler's Data on the Human Sex Ratio}

\description{
Geissler (1889) published data on the distributions of boys and girls in families in 
Saxony, collected for the period 1876-1885. The \code{Geissler} data tabulates 
the family composition of 991,958 families by the number of boys and girls
listed in the table supplied by Edwards (1958, Table 1).
}
\usage{data(Geissler)}
\format{
  A data frame with 90 observations on the following 4 variables.  The rows represent the
  non-NA entries in Edwards' table.
  \describe{
    \item{\code{boys}}{number of boys in the family, \code{0:12}}
    \item{\code{girls}}{number of girls in the family, \code{0:12}}
    \item{\code{size}}{family size: \code{boys+girls}}
    \item{\code{Freq}}{number of families with this sex composition}
  }
}
\details{
The data on family composition was available because, on the birth of a child,
the parents had to state the sex of all their children on the birth certificate.
These family records are not necessarily independent, because a given family
may have had several children during this 10 year period, included as 
multiple records.
}
\source{
Edwards, A. W. F. (1958).
An Analysis Of Geissler's Data On The Human Sex Ratio.
\emph{Annals of Human Genetics}, 
23, 6-15.
}
\references{
Friendly, M. and Meyer, D. (2016). 
\emph{Discrete Data Analysis with R: Visualization and Modeling Techniques for Categorical and Count Data}. 
Boca Raton, FL: Chapman & Hall/CRC. \url{http://ddar.datavis.ca}.

Geissler, A. (1889).
\emph{Beitrage zur Frage des Geschlechts verhaltnisses der Geborenen}
Z. K. Sachsischen Statistischen Bureaus, 35, n.p.

Lindsey, J. K. & Altham, P. M. E. (1998). 
Analysis of the human sex ratio by using overdispersion models.
\emph{Journal of the Royal Statistical Society: Series C (Applied Statistics)}, 
47, 149-157. 
}
\seealso{
\code{\link[vcd]{Saxony}}, containing the data for families of size 12.
}
\examples{
data(Geissler)
str(Geissler)

# reproduce Saxony data, families of size 12
Saxony12<-subset(Geissler, size==12, select=c(boys, Freq))
rownames(Saxony12)<-NULL

# make a 1-way table
xtabs(Freq~boys, Saxony12)

# extract data for other family sizes
Saxony11<-subset(Geissler, size==11, select=c(boys, Freq))
rownames(Saxony11)<-NULL
Saxony10<-subset(Geissler, size==10, select=c(boys, Freq))
rownames(Saxony10)<-NULL

}
\keyword{datasets}
