# effect size

1. ### Calculating effect size for a within group comparison of score before&after treatment

Hi all, :wave: I am wondering which formula will be more suitable for calculating effect size (Cohen's d) of an intervention with scores obtained before (1 score) & after treatment (1 score) in the same group of individuals. :confused: As I had two scores, I used paired t-test for for within...
2. ### Calculating effect size for generalized linear model?

Hi, I have carried out a generalized linear model (in SPSS) with one dependent variable and two factors. Both factors have multiple categories (ie. one factor has three 'groups', the other four). I would like to calculate the effect size for each factor. I have found a lot of information...
3. ### Calculation of effect size in Hierarchical regression

Hello there, I have conducted a hierarchical regression with two steps. Statistical significance resulted form the first step, as the second step did not seem to add any value to the model. How could I calculate the effect size of the model? And more specifically: Suppose that we have...
4. ### Standard deviation of the mean difference out of Pre/Post Test Descriptive Statistics

I have several RCT pre/post intervention studies that I am calculating Hedge's g for. All of the studies report the difference of mean and difference of standard deviation between pre/post for each group except one. I know how to calculate the difference of mean [= Mean(post)-Mean(pre)], but...
5. ### Moderated Mediation when Independent Variable is also the moderator

I have a question on a special case of moderated mediation... I want to compare some effect sizes of: a "simple moderation model" with a "moderated mediation model in which the IV is also a moderator". I don't have data yet. But I want to know if the betas (effect sizes) explained in...
6. ### What is the difference between statistical significance (based on probability) and...

(Questions wouldn't fit) What is the difference between statistical significance (based on probability) and an effect size? I am fairly new to stats and finding a bit of an up hill marathon at the moment. I have been asked to research the question posted above, yet I have exhausted my...
7. ### Does n Affect Effect Size

We all know the pvalues are affected by sample size. I've had profs claim that effect size is unaffected by sample size. But I'm thinking this may not be true. Let's take standardized mean difference with the pooled sd in the denominator: where... and where... and also... I'm not...
8. ### effect size to report or not

I challenged a prof today and I said that an effect size should not be reported for non significant results. He strongly disagreed. What are your thoughts (I'm ok if I'm wrong but I want to know why). If anyone has specific sources to cite that would be awesome.
9. ### Comparing two methods to measure disease severity

I am testing a new, fast method to score disease severity in an animal model of a human disease. M appears to be less sensitive than the gold standard scoring method, G. G is discrete and has a range (0,1,2...20). M is continuous and varies from 0 to 1. The linear correlation coef between...
10. ### Calculating effect size.

Hi, I'm learning about ANOVA's and understand that to report results I have to calculate effect size. We have been taught to calculate W^2 (Omega squared) first and then carry on with comparison tests. Can you tell me if the W^2 has to be significant before computing comparison tests or is...
11. ### effect size for McNemar's?

Is it possible to calculate effect size for comparisons made using the McNemar's test? If so, how? I am at a total loss on this after spending A LOT of time combing the web. I would be so grateful if anyone had any ideas!
12. ### 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...
13. ### Eefect size

Hi.. i have a question on effect size..i get a negative value of effect size..should i report it as an absolute value or a negative value.. and one more thing, if i swapped the means and SD in the effect size calculator,,i get the same value minus the negative sign...how do i determine...
14. ### Determining error of a slope based on a dependent variable containing error

I am currently attempting to compare the slopes of many linear graphs. Each graph is a plot of Time (independent variable) vs. Effect Size (dependent variable). I know the standard error associated with each measure of Effect Size. I want to know the error of the slope of each graph. However...
15. ### Effect Size measure for Ordinal Logistic Regression

Hello friends, I am using "Ordinal Logistic Regression" for my dissertation research. I wanted to report the effect size but couldn't find definitive reference for reporting an effect size. I have found some papers stating that "Nagelkere's R square" is the effect size measure. Another states...
16. ### Effect size for Wilcoxon Signed Rank

1) i want to calculate the effect size for wilcoxon signed rank (paired sample). I have one group of 10 participants. I know the formula for the effect size is Z/squaroot of N. My question is, does N refer to the numbe of participant (N=10) or should I multiply the number of participant...
17. ### Help interpreting a statistical symbol "Φ"

Hello, Please excuse my ignorance - novice. I am currently reading a paper - 'Non-parametric estimators of effect size' by Larry V. Hedges and Ingram Olkin. The problem is that i can not understand this Symbol 'Φ'. Could someone please tell me what this means is statistics. Yes,I have...
18. ### Help with power analysis!

So, I've never taken a statistics course before. Just completed my honors thesis and graduated. Now I'm trying to do power analysis (post hoc) on my data. Using G power, please help me with what to do/how to interpret the results. First of all, I looked at two independent groups (group 1...
19. ### effect sizes: generalized omega squared statistics

hi all i read this paper http://www.psych.umn.edu/courses/spring06/federicoc/psy8815/lectures/genomegasquared.pdf and based on the following arguments: 1) very small sample size - needs unbiased estimation 2) repeated measures 3) 2 x 2 design decided on reporting the generalized...
20. ### Power calculation in regression for curviliear effect

Hi! I performed a regresson analysis to test a curvilinear effect. I've followed Aiken & West procedures Center X, Squared centered X Enter X 1st step Enter X2 2nd step However, in the interpretation of the results I would like to test the power of this regression, considering the...