About
(dependent|paired sample) t-test in R
- The Mean of differences is the point estimate
- The confidence interval is the interval estimate around the mean difference (not around the mean of the samples)
Articles Related
Package
stats
dependent t-test
t.test(data$pre, data$post, paired = T)
Paired t-test
data: data$pre and data$post
t = -9.0089, df = 39, p-value = 4.511e-11
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
-2.41843 -1.53157
sample estimates:
mean of the differences
-1.975
lsr
Effect size
<MATH> \text{Cohen's d} = \frac{\text{Mean of difference scores}}{\text{Standard deviation of difference scores}} </MATH>
cohensD(data$post, data$post, method="paired")
[1] 0.4485912