fanova: Flexible anova

In rosetta: Parallel Use of Statistical Packages in Teaching

Flexible anova

Description

This function is meant as a userfriendly wrapper to approximate the way analysis of variance is done in SPSS.

Usage

fanova(
  data,
  y,
  between = NULL,
  covar = NULL,
  withinReference = 1,
  betweenReference = NULL,
  withinNames = NULL,
  plot = FALSE,
  levene = FALSE,
  digits = 2,
  contrast = NULL
)

## S3 method for class 'fanova'
print(x, digits = x$input$digits, ...)

Arguments

data	The dataset containing the variables to analyse.
y	The dependent variable. For oneway anova, factorial anova, or ancova, this is the name of a variable in dataframe data. For repeated measures anova, this is a vector with the names of all variable names in dataframe data, e.g. c('t0_value', 't1_value', 't2_value').
between	A vector with the variables name(s) of the between subjects factor(s).
covar	A vector with the variables name(s) of the covariate(s).
withinReference	Number of reference category (variable) for within subjects treatment contrast (dummy).
betweenReference	Name of reference category for between subject factor in RM anova.
withinNames	Names of within subjects categories (dependent variables).
plot	Whether to produce a plot. Note that a plot is only produced for oneway and twoway anova and oneway repeated measures designs: if covariates or more than two between-subjects factors are specified, not plot is produced. For twoway anova designs, the second predictor is plotted as moderator (and the first predictor is plotted on the x axis).
levene	Whether to show Levene's test for equality of variances (using car's leveneTest function but specifying mean as function to compute the center of each group).
digits	Number of digits (actually: decimals) to use when printing results. The p-value is printed with one extra digit.
contrast	This functionality has been implemented for repeated measures only.
x	The object to print (i.e. as produced by regr).
...	Any additional arguments are ignored.

Details

This wrapper uses oneway and lm and lmer in combination with car's Anova function to conduct the analysis of variance.

Value

Mainly, this function prints its results, but it also returns them in an object containing three lists:

input	The arguments specified when calling the function
intermediate	Intermediat objects and values
output	The results such as the plot.

Author(s)

Gjalt-Jorn Peters and Peter Verboon

Maintainer: Gjalt-Jorn Peters [e-mail]

See Also

regr and logRegr for similar functions for linear and logistic regression and oneway, lm, lmer and Anova for the functions used behind the scenes.

Examples

### Oneway anova with a plot
fanova(dat=mtcars, y='mpg', between='cyl', plot=TRUE);

### Factorial anova
fanova(dat=mtcars, y='mpg', between=c('vs', 'am'), plot=TRUE);

### Ancova
fanova(dat=mtcars, y='mpg', between=c('vs', 'am'), covar='hp');

### Don't run these examples to not take too much time during testing
### for CRAN
## Not run: 
### Repeated measures anova; first generate datafile
dat <- mtcars[, c('am', 'drat', 'wt')];
names(dat) <- c('factor', 't0_dependentVar' ,'t1_dependentVar');
dat$factor <- factor(dat$factor);

### Then do the repeated measures anova
fanova(dat, y=c('t0_dependentVar' ,'t1_dependentVar'),
       between='factor', plot=TRUE);

## End(Not run)

rosetta documentation built on March 7, 2023, 7:40 p.m.