g_ind_t: d_g Corrected for Independent t
In MOTE: Effect Size and Confidence Interval Calculator

g_ind_t

R Documentation

`d_g` Corrected for Independent `t`

Description

This function displays d_g (Hedges' g) corrected and the non-central confidence interval for independent t.

Usage

g_ind_t(m1, m2, sd1, sd2, n1, n2, a = 0.05)

g.ind.t(m1, m2, sd1, sd2, n1, n2, a = 0.05)

Arguments

`m1`	mean group one
`m2`	mean group two
`sd1`	standard deviation group one
`sd2`	standard deviation group two
`n1`	sample size group one
`n2`	sample size group two
`a`	significance level

Details

The small-sample correction factor is:

\mathrm{correction} = 1 - \frac{3}{4(n_1 + n_2) - 9}

d_g is computed as the standardized mean difference multiplied by the correction:

d_g = \frac{m_1 - m_2}{s_{\mathrm{pooled}}} \times \mathrm{correction}

Learn more on our example page.

Value

d: d_g corrected effect size
dlow: lower level confidence interval for d_g
dhigh: upper level confidence interval for d_g
M1: mean of group one
sd1: standard deviation of group one
se1: standard error of group one
M1low: lower level confidence interval of mean one
M1high: upper level confidence interval of mean one
M2: mean of group two
sd2: standard deviation of group two
se2: standard error of group two
M2low: lower level confidence interval of mean two
M2high: upper level confidence interval of mean two
spooled: pooled standard deviation
sepooled: pooled standard error
correction: Hedges' small-sample correction factor
n1: sample size of group one
n2: sample size of group two
df: degrees of freedom (n_1 - 1 + n_2 - 1)
t: t-statistic
p: p-value
estimate: the d_g statistic and confidence interval in APA style for markdown printing
statistic: the t-statistic in APA style for markdown printing

Examples


# The following example is derived from the "indt_data"
# dataset, included in the MOTE library.

# A forensic psychologist conducted a study to examine whether
# being hypnotized during recall affects how well a witness
# can remember facts about an event. Eight participants
# watched a short film of a mock robbery, after which
# each participant was questioned about what he or she had
# seen. The four participants in the experimental group
# were questioned while they were hypnotized. The four
# participants in the control group received the same
# questioning without hypnosis.

   t.test(correctq ~ group, data = indt_data)

# You can type in the numbers directly, or refer to the dataset,
# as shown below.

    g_ind_t(m1 = 17.75, m2 = 23, sd1 = 3.30,
           sd2 = 2.16, n1 = 4, n2 = 4, a = .05)

    g_ind_t(17.75, 23, 3.30, 2.16, 4, 4, .05)

    g_ind_t(mean(indt_data$correctq[indt_data$group == 1]),
            mean(indt_data$correctq[indt_data$group == 2]),
            sd(indt_data$correctq[indt_data$group == 1]),
            sd(indt_data$correctq[indt_data$group == 2]),
            length(indt_data$correctq[indt_data$group == 1]),
            length(indt_data$correctq[indt_data$group == 2]),
            .05)

# Contrary to the hypothesized result, the group that underwent hypnosis were
# significantly less accurate while reporting facts than the control group
# with a large effect size, t(6) = -2.66, p = .038, d_g = 1.64.

MOTE documentation built on Dec. 15, 2025, 9:06 a.m.