| % File src/library/datasets/man/ChickWeight.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2011 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{ChickWeight} |
| \docType{data} |
| \alias{ChickWeight} |
| \title{Weight versus age of chicks on different diets} |
| \description{ |
| The \code{ChickWeight} data frame has 578 rows and 4 columns from an |
| experiment on the effect of diet on early growth of chicks. |
| } |
| \usage{ChickWeight} |
| \format{ |
| An object of class |
| \code{c("nfnGroupedData", "nfGroupedData", "groupedData", "data.frame")} |
| containing the following columns: |
| \describe{ |
| \item{weight}{ |
| a numeric vector giving the body weight of the chick (gm). |
| } |
| \item{Time}{ |
| a numeric vector giving the number of days since birth when |
| the measurement was made. |
| } |
| \item{Chick}{ |
| an ordered factor with levels |
| \code{18} < \dots < \code{48} |
| giving a unique identifier for the chick. The ordering of |
| the levels groups chicks on the same diet together and |
| orders them according to their final weight (lightest to |
| heaviest) within diet. |
| } |
| \item{Diet}{ |
| a factor with levels 1, \dots, 4 indicating which |
| experimental diet the chick received. |
| } |
| } |
| } |
| \details{ |
| The body weights of the chicks were measured at birth and every |
| second day thereafter until day 20. They were also measured on day |
| 21. There were four groups on chicks on different protein diets. |
| |
| This dataset was originally part of package \code{nlme}, and that has |
| methods (including for \code{[}, \code{as.data.frame}, \code{plot} and |
| \code{print}) for its grouped-data classes. |
| } |
| \source{ |
| Crowder, M. and Hand, D. (1990), \emph{Analysis of Repeated Measures}, |
| Chapman and Hall (example 5.3) |
| |
| Hand, D. and Crowder, M. (1996), \emph{Practical Longitudinal Data |
| Analysis}, Chapman and Hall (table A.2) |
| |
| Pinheiro, J. C. and Bates, D. M. (2000) \emph{Mixed-effects Models in |
| S and S-PLUS}, Springer. |
| } |
| \seealso{ |
| \code{\link{SSlogis}} for models fitted to this dataset. |
| } |
| |
| \examples{\donttest{ |
| require(graphics) |
| coplot(weight ~ Time | Chick, data = ChickWeight, |
| type = "b", show.given = FALSE) |
| }} |
| \keyword{datasets} |