R/oneway.R

In jgkwes/oneway: One-way Analysis of Variance

#'@title One Way Analysis of Variance
#'
#'@description 
#'\code{oneway} computes a one-way analysis of variance and inclues group
#'level summary statistics.
#'
#'@details
#'This function computes a standard one-way ANOVA, means, and standard
#'deviations.  Missing values are handled via list-wise deletion.
#'
#'@param formula an object of class formula, relating the dependent variable
#'to the grouping variable.
#'@param data  a data frame containing the variables in the model.
#'
#'@export 
#'
#'
#'@return a list with 2 elements:
#'\item{oneway}{a list with the lm results}
#'\item{summarystats}{a data frame with the summary statisitics}
#'
#'@author Kelly Jamrog <kjamrog@@wesleyan.edu>
#'
#'@examples 
#'mileage <- oneway(hwy~class, cars)
#'summary(mileage)
#'mileage
#'plot(mileage)


oneway <- function(formula, data) {
  
  # listwise deletion of missing values
  data_complete <- na.omit(data)
  
  # anova
  fit <- lm(formula, data_complete)
  
  stats <-  aggregate(formula,
                      data,
                      function(x) c(n = length(x), mean = mean(x), sd = sd(x)))
  
  
  result <- list(anova = fit, summarystats = stats)
  class(result) <- c("oneway", "list")
  return(result)
  
}