# d.dep.t.diff.t: d from t for Repeated Measures with SD Difference Scores... In MOTE: Effect Size and Confidence Interval Calculator

## Description

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.

## Usage

 `1` ```d.dep.t.diff.t(t, n, a = 0.05) ```

## Arguments

 `t` t-test value `n` sample size `a` significance level

## Details

To calculate d, the t-statistic is divided by the square root of the sample size.

d_z = t / sqrt(n)

## Value

 `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

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24``` ```#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. ```

MOTE documentation built on May 2, 2019, 5:51 a.m.