jmv (version 0.7.3.1)

ttestIS: Independent Samples T-Test

Description

Independent Samples T-Test

Usage

ttestIS(data, vars, group, students = TRUE, bf = FALSE, bfPrior = 0.707,
  welchs = FALSE, mann = FALSE, hypothesis = "different", norm = FALSE,
  eqv = FALSE, meanDiff = FALSE, effectSize = FALSE, ci = FALSE,
  ciWidth = 95, desc = FALSE, plots = FALSE, miss = "perAnalysis")

Arguments

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

students

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

bf

TRUE 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

welchs

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

mann

TRUE 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

norm

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

eqv

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

meanDiff

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

effectSize

TRUE or FALSE (default), provide effect sizes

ci

TRUE or FALSE (default), provide confidence intervals

ciWidth

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

desc

TRUE or FALSE (default), provide descriptive statistics

plots

TRUE 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.

Examples

data('ToothGrowth')

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

#
#  Independent Samples T-Test
#
#  Independent Samples T-Test
#  ----------------------------------------------------
#                          statistic    df      p
#  ----------------------------------------------------
#    len    Student's t         1.92    58.0    0.060
#  ----------------------------------------------------
#