effect size

  1. N

    Calculating and Reporting Effect Size for Fisher's Exact Test?

    Hi everyone, I am writing a paper for publication. This is my first time doing a survey study, and also my first time working with categorical data (I, like many people unfortunately, have learned statistics bit by bit, as I have needed it in my research). The journal I am submitting to...
  2. N

    Post-Hoc Power Analysis (G*Power) for simple linear regression

    Hey everyone! I conducted a simple linear regression with non-significant results. Now I would like to analyze the power of this calculation using G*Power. I chose the option "F-tests - Linear multiple regression, fixedmodel, R(2) deviation from zero and entered 1 as my numer of predictors...
  3. J

    Confidence interval for Cohen's H

    hi everyone, I would like to create a Forest plot for a number of studies that looked at proportions. I calculated effect sizes using Cohen's H, but now I need to know the confidence intervals for those effect sizes. Does one of you know how to calculate those? Thanks in advance!
  4. C

    Effect Sizes

    This may seem like a ridiculous question, but it's bugging me and no text book or paper I've read has answered it. I am looking into research on effect sizes and their use in research. I see a lot of mention of Cohen's D and F2 and the "small", "medium" and "large" effect sizes. Can someone...
  5. D

    Using Pre-Post data in a meta-analysis

    Hello, I am trying to figure out the best way to calculate an effect size for a single-group design when I do not know the pair-wise correlation or standard deviation for the difference scores. I have received mixed messages as to whether or not I can use the formula for independent measures...
  6. G

    Repeated Measures Design & Effect Sizes, Normality

    My question is about calculating effect sizes for a repeated measures design with a small sample size. I want to calculate Cohen's d.av (as recommended by Lakens, 2013 and others) instead of d.z (which you can compute using just your t-value and N), since the latter tends to overestimate your...
  7. K

    Relationship between effect size, sample size and p-value?

    Is there a simple formula that links effect size, sample size and p-value? Specifically, how does the p-value depend on effect size and sample size? Are there any other critical factors involved in this relationship? I'm basically looking to understand how these factors are linked...
  8. T

    please help me justify sample size for a pilot clinical trial

    I'm a bit desperate for statistical help so trying out all avenues. Any guidance appreciated! I need to justify a sample size of 30 or 32 (15 or 16 per arm) for a placebo-controlled pilot clinical trial of a drug. This is all I can afford, but that is not a good enough justification for...
  9. B

    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...
  10. D

    How to calculate sample size and effect size for comparing means from two groups

    Hi all, hoping i can find some answers here for a bit of a problem i am having regarding a sample size calculation for a study I am soon to conduct. The population size is 64 and fixed. 32 control and 32 intervention. No drop outs will occur in this trial. There will be a pre (baseline) test...
  11. V

    Report effect size?

    Hi, I am new to this forum and my knowledge about statistic is pretty basic. So beforehand I thank you for your help. In my research I used non parametric tests to compare two groups´ academic performance. It had a quasi-experimental design where the groups were not randomly selected but were...
  12. M

    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...
  13. M

    Comparing the Power and Effect Size from Different Studies

    Hi there Talk Stats Community, I am an undergraduate research assistant. Currently I am doing research on a project, and our results have indicated something that is quite different from previous findings. We have used a more specific and sensitive test to prove that a particular microbe...
  14. M

    Is there a difference between z-score and effect size?

    I just started teaching statistics to myself (I never had it in school but will need it when I start University). I have problems with z-scores and effect size. I think that you use a z-score if you want to know how a score compares to the mean or standard derivation. And you use the effect...
  15. S

    Bigger sample size and less good results or smaller sample size but better results

    I hope this is the right place to post this question. I'm doing my thesis based upon the data of my professors research study. I want to look into wether 2 different psychological treatment conditions affect social phobia compared to a control group, how they differ, and wether former...
  16. A

    power analysis- interpreting sample size given established literature

    Hello and thank you for clicking, I am attempting to use relevant effects size from a published study to obtain a suggested sample size for my related study in G*power. However, 1) the previous study only compared 2 groups w/ t-test and I want to compare 5 with one way ANOVA and 2) the...
  17. N

    Power analysis (gpower) - interactions

    I'd like to conduct a power analysis in gpower to determine the total N required in a study, with the following requirements: power desired: 0.80 alpha: .05 effect size: unsure what to use here (explained below) study design: 2x2 within subjects anova (4 conditions) where my main...
  18. B

    Calculating effect size with interaction term

    If I am running multiple regression in r, what is the next step in order to get the effect size for all variables when there's also an interaction term in the equation. For example: model=lm(DV ~ Var1 + Var2 + Var2:Var3) Also, what's the best way to determine whether or not to do an...
  19. A

    MLR equivalent for repeated measures, multiple correlated responses

    I'd like to determine the best approach to determining effect sizes for a set of experimental data with multiple correlated responses. Due to repeated measurements and high correlation between responses, I know that a simple multiple linear regression model obviously isn't the answer. The...
  20. R

    Semipartial correlations for simple slopes

    Hello! I'm in need of some help for calculating sr2 for simple slopes. Here is my situation: I'm using SPSS. I have three IVs: x1: dichotomous and coded -1,1 x2: dichotomous and coded -1,1 x3: continuous centered variable I have a 3 way interaction that I've calculated the simple...