anova1way {stats4teaching}

One-Way ANOVA

Description

anova1way is used to generate multivariate data in order to compute analysis of variance with 1 factor. It provides balanced and unbalanced ANOVA (as long as homogeneity of variances is satisfied. In other case it is provided Welch test).

Usage

anova1way(k = 3,n , mean = 0, sigma = 1,
          coefvar = NULL, method = c("Tukey", "LSD", "Dunnett", "Bonferroni", "Scheffe"),
          conf.level = 0.95, dec = 2)

Arguments

k

number of levels. By default k = 3.

n

size of samples.

mean

vector of means.

sigma

vector of standard deviations.

coefvar

an optional vector of coefficients of variation.

method

post-hoc method applied. There are five possible choices: "Tukey", "LSD", "Dunnett", "Bonferroni", "Scheffe". Can be specified just the initial letter.

conf.level

confidence level of the interval.

dec

number of decimals for observations.

Details

If mean or sigma are not specified it is assumed the default values of 0 and 1.

If coefvar (= sigma/mean) is specified, function omits sigma.

Number of samples is choosen by k (by default k = 3). Therefore, if the others parameters (n, mean, sigma, coefvar) have not same length, function rep will be used. Pay attention if vectors dont have same length.

Moreover, not only gives samples for each level, but also the ANOVA table and post-hoc test (in case of significance). By default conf.level = 0.95 and Tukey method is used. If the homogeneity of variances is not verified (using Bartlett test), the Welch test is performed.

Value

List containing the following components:

• Data: a data frame containing the samples created.

• Anova: anova fitted model.

• Significance: significance of the factor.

• Size.effect: size effect of the factor.

• Test Post-Hoc: test Post-Hoc.

Examples

anova1way(k=4,n=c(40,31,50),mean=c(55,52,48,59),coefvar=c(0.12,0.15,0.13),conf.level = 0.99)

anova1way(k=3,n=15,mean=c(10,15,20),sigma =c(1,1.25,1.1),method ="B")