# cohen's d

1. ### Cohen's d interpretation

The book says: 0.2 - small 0.5 - medium 0.8 - large I know that Cohen's interpretation is only a rule of thumb, so I'm not sure if there is a "one" answer. but what is the interpretation when d is between the values? Is d=0.3 small? or medium? Option 1 Range interpretation 0-0.2...
2. ### Transforming mean difference to Cohen´s d in a meta-analysis

I wish to transform the MD to standardized MD. For pregabalin the mean difference is -33.14. As far as I understand one way to achieve the above is to calculate the pooled SD using the 95% confidence interval estimate(s). SD = (-53.98-(-33.14))/1.96*sqrt(235+151) = 208.898 Hence, the Cohen´s...
3. ### Effect Size - Cohen's D calculation

I had a question about how to calculate Cohen's D a particular situation for my meta-analysis. I am a first year grad student, so my familiarity with statistics is somewhat limited! The study design - participants are assigned to one of two groups (parallel design), but not a true RCT because...
4. ### How to report t-test, CIs, cohen's d etc of log-transformed data

I am wondering what is best/normal practice for reporting the results of an independent t-test of log-transformed data? For context, I am comparing the value of household assets for children who are attending pre-primary school with children who are NOT attending pre-primary school in Uganda...
5. ### Sensitivity analysis said I wouldn't find an effect less than .8 but I did!

Hello! I ran a sensitivity analysis on G*power and it told me that for my independent samples t test (10 people per group, alpha = .05, power =.8) I wouldn't find an effect size smaller than d = 1.32. I then ran the t test and got a significant result with an d = 1.15 How is this possible?
6. ### SOS action research project question

Firstly, I am grateful for any assistance. I am a novice who tries hard :yup: I am trying to write up the results section for a report and have completed a paired t test and Cohen's d using pre and post data sets from same group: 35 students I have completed the test and worked the math...
7. ### Using effect sizes to determine questionnaire sensitivity

Hi guys, I ran a therapeutic group with 6 people and got them to complete 5 questionnaires before the group and repeat them after the group. I'm now writing this up as a report and I know I can't carry out t-tests as the sample size is so small, but I have been advised to report effect sizes...
8. ### What would you do if you had two very different Values of Cohen's D?

I conducted a factorial ANOVA.. and I found a significant interaction. I used two independent samples t-tests to conduct a further simple effects analysis one group always had higher accuracy than the other group regardless of the condition. However: condition 1 had an extremely...
9. ### Regarding Cohen's d use...

Hi, I am confused regarding added value of Cohen's d. Consider a case of paired t-test. I calculate the Cohen's d as: mean(vec1) - mean(vec2)) / population_std; population_std: standard deviation of x – y. 1. I am said that p-value is not informative enough because effect size might be...
10. ### Meta-Analysis: Transforming F scores to Cohen's d

I need to convert F statistics from 1-Way & from 2-Way ANOVAs into Cohen's d. The formula in my handbook: d = (2 * the square root of F) /over/ (the square root of df(error)) My question is: Is df(error) equal to (N - k) - (n - 1)? Or does "error" denote something else? If anyone has a...
11. ### Effect sizes and repeated measures

Hi there, I am doing a bit of research looking at the effects of repeat test taking. Students are allowed to take a test multiple times. I have a dataset including student scores on each iteration of the test. I have done a repeated measures ANOVA to try to determine whether scores...
12. ### Comparison of the cohen's ds of 2 independent studies

Hello, Is it possible to statistically compare the cohen's d of two studies in order to determine of one of the two Cohen's d is statistically significantly larger (or smaller) than the other one? I have calculated Cohen's d for two virtually identical studies. In one study the cohen's d for...
13. ### Cohen's d for one-sample/paired-samples vs. independent samples, and pooled SDs

I have a few questions for you all about Cohen's d and pooled SDs! This is my first post, hope it goes in line with forum guidelines. 1) one-sample / paired-sample vs. independent samples Cohen's d calculation It seems that for calculation of Cohen's d (an estimate of effect size), you...
14. ### Making claims about effect size

Hi, I'm working with a very large sample, and have realized that almost any blip in the data will register as p=0.000 due to the sample size. Of course there is a big difference between statistical significance and actual significance. I've been reading up on strategies for calculating...