Independent Samples T-Test

Example usage

 ttestIS(data, vars='len', group='supp')


data — the data as a data frame

vars — a vector of strings naming the dependent variables

group — a string naming the grouping variable, must have 2 levels

studentsTRUE (default) or FALSE, perform Student's t-tests

bfTRUE or FALSE (default), provide Bayes factors

bfPrior — a number between 0.5 and 2 (default 0.707), the prior width to use in calculating Bayes factors

welchsTRUE or FALSE (default), perform Welch's t-tests

mannTRUE or FALSE (default), perform Mann-Whitney U tests

hypothesis'different' (default), 'oneGreater' or 'twoGreater', the alternative hypothesis; group 1 different to group 2, group 1 greater than group 2, and group 2 greater than group 1 respectively

normTRUE or FALSE (default), perform Shapiro-Wilk test of normality

eqvTRUE or FALSE (default), perform Levene's test for equality of variances

meanDiffTRUE or FALSE (default), provide means and standard errors

effectSizeTRUE or FALSE (default), provide effect sizes

ciTRUE or FALSE (default), provide confidence intervals

ciWidth — a number between 50 and 99.9 (default: 95), the width of confidence intervals

descTRUE or FALSE (default), provide descriptive statistics

plotsTRUE or FALSE (default), provide descriptive plots

miss'perAnalysis' or 'listwise', how to handle missing values; 'perAnalysis' excludes missing values for individual dependent variables, 'listwise' excludes a row from all analyses if one of its entries is missing.