| d.dep.t.diff.t | R Documentation |
This function displays d for repeated measures data and the non-central confidence interval using the standard deviation of the differences as the denominator estimating from the t-statistic.
d.dep.t.diff.t(t, n, a = 0.05)
t |
t-test value |
n |
sample size |
a |
significance level |
To calculate d, the t-statistic is divided by the square root of the sample size.
d_z = t / sqrt(n)
Learn more on our example page.
d |
effect size |
dlow |
lower level confidence interval d value |
dhigh |
upper level confidence interval d value |
n |
sample size |
df |
degrees of freedom (sample size - 1) |
p |
p-value |
estimate |
the d statistic and confidence interval in APA style for markdown printing |
statistic |
the t-statistic in APA style for markdown printing |
#The following example is derived from the "dept_data" dataset included
#in the MOTE library.
#In a study to test the effects of science fiction movies on people’s belief
#in the supernatural, seven people completed a measure of belief in
#the supernatural before and after watching a popular science
#fiction movie. Higher scores indicated higher levels of belief.
scifi = t.test(dept_data$before, dept_data$after, paired = TRUE)
#The t-test value was 1.43. You can type in the numbers directly,
#or refer to the dataset, as shown below.
d.dep.t.diff.t(t = 1.43, n = 7, a = .05)
d.dep.t.diff.t(1.43, 7, .05)
d.dep.t.diff.t(scifi$statistic, length(dept_data$before), .05)
#The mean measure of belief on the pretest was 5.57, with a standard
#deviation of 1.99. The posttest scores appeared lower (M = 4.43, SD = 2.88)
#but the dependent t-test was not significant using alpha = .05,
#t(7) = 1.43, p = .203, d_z = 0.54. The effect size was a medium effect suggesting
#that the movie may have influenced belief in the supernatural.