selfea (version 1.0.1)

ttest_cohens_d: ttest_cohens_d

Description

Fulfill Welch Two Sample t-test (t.test) and calculate Cohen's d as well as determine significance by p-value and effect size threshold.

Usage

ttest_cohens_d(values, groups, alpha = 0.05, power = 0.9, alternative = "two.sided", paired = FALSE, var.equal = FALSE)

Arguments

values

A scalar vector. Length of both of two vectors, values and groups, should be same.

groups

Experiment groups for the vector 'values'. Length of both of two vectors, values and groups, should be same. The number of groups is not limited to two, such as group <- c('A','A','A','B','B').

alpha

P-value threshold

power

Give the statistical power you desired for output significant list

alternative

Choose one of these c("two.sided", "less", "greater"). Default is "two.sided".

paired

if two groups are paired, set it to TRUE. Default is FALSE.

var.equal

if two groups are assumed to have same variance, set it to TRUE. Default is FALSE.

Value

A list containing the followings:

observed_pvalue

Calculated P-value from T-test

observed_cohens_d

Calculated Cohen's f

threshold_cohens_d

Cohen's d threshold at the desired power

threshold_pvalue

Desired p-value threshold

flag_pvalue

TRUE=passed the pvalue threshold, FALSE=not

flag_cohens_d

TRUE=passed the Cohen's d threshold, FALSE=not

power_desired

Statistical power in you input parameters

method

'Welch Two Sample t-test'

alternative

alternative option in you input parameters

paired

paired option in you input parameters

var.equal

var.equal option in you input parameters

Examples

library(selfea)

values <- c(8,10,8,8,11,29,26,22,27,26)
groups <- c("U200","U200","U200","U200","U200","U600","U600","U600","U600","U600")
list_result <- ttest_cohens_d (values, groups, 0.05, 0.90)