1% File src/library/datasets/man/npk.Rd 2% Part of the R package, https://www.R-project.org 3% copyright (C) 1999 W. N. Venables and B. D. Ripley 4% Distributed under GPL 2 or later 5 6\name{npk} 7\alias{npk} 8\title{ 9 Classical N, P, K Factorial Experiment 10} 11\description{ 12 A classical N, P, K (nitrogen, phosphate, potassium) factorial 13 experiment on the growth of peas conducted on 6 blocks. Each half of a 14 fractional factorial design confounding the NPK interaction was used 15 on 3 of the plots. 16} 17\usage{ 18npk 19} 20\format{ 21 The \code{npk} data frame has 24 rows and 5 columns: 22 \describe{ 23 \item{\code{block}}{ 24 which block (label 1 to 6). 25 } 26 \item{\code{N}}{ 27 indicator (0/1) for the application of nitrogen. 28 } 29 \item{\code{P}}{ 30 indicator (0/1) for the application of phosphate. 31 } 32 \item{\code{K}}{ 33 indicator (0/1) for the application of potassium. 34 } 35 \item{\code{yield}}{ 36 Yield of peas, in pounds/plot (the plots were (1/70) acre). 37 } 38 } 39} 40\source{ 41 Imperial College, London, M.Sc. exercise sheet. 42} 43\references{ 44 Venables, W. N. and Ripley, B. D. (2002) 45 \emph{Modern Applied Statistics with S.} Fourth edition. Springer. 46} 47% This gets different roundings 48\examples{\donttest{ 49options(contrasts = c("contr.sum", "contr.poly")) 50npk.aov <- aov(yield ~ block + N*P*K, npk) 51npk.aov 52summary(npk.aov) 53coef(npk.aov) 54options(contrasts = c("contr.treatment", "contr.poly")) 55npk.aov1 <- aov(yield ~ block + N + K, data = npk) 56summary.lm(npk.aov1) 57se.contrast(npk.aov1, list(N=="0", N=="1"), data = npk) 58model.tables(npk.aov1, type = "means", se = TRUE) 59}} 60\keyword{datasets} 61