Questions tagged [effect-size]

Effect size is "a measure of the strength of a phenomenon or a sample-based estimate of that quantity" [Wikipedia].

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Power and sample size estimations, how to standardize and compare to previous research. MLR or Correlation for effect size?

Ok, there are a couple of questions here to be honest, Background: I am assessing if thinking,(INFP (Likert scale, 4 subscales) and CT (Likert, two subscales) predict (other-rated) perceptions of ...
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Compute Cohen's f for ANOVA (k = 3 groups) using largest pairwise difference Cohen's d for power analysis - which formula?

I am attempting to compute Cohen's $f$ from expected pairwise Cohen's $\delta$ values in $k=3$ independent groups. I intend to use this value in a power analysis ahead of a data collection. I want ...
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Calculate Cohen's d for pairwise tukey tests in a 1-way ANOVA

I have the following dilemma: Design: 1 (Group: Patient vs. Control_1 vs. Control_2) between-factors design arrayed as a 1-way ANOVA Analysis: Following a main effect of group perform I perform all ...
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How to convert beta from logistic regression into cohen's d?

Is there a way to transform a coefficient from a logistic regression into a cohen's d value? I am trying to calculate the cohen's d for a study with a binary DV while controlling for another ...
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How to convert sampling sampling variances for a meta-analysis using raw means as effect sizes?

I am conducting a meta-analysis using raw mean scores as effect sizes (i.e., reported test scores on a certain standardized test). I found a calculation formula for sampling variances provided by, e....
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42 views

Meta-analyses using raw mean as Effect Size, instead of mean differences (e.g., Cohen's d)

I am writing up my meta-analysis using raw mean scores as effect sizes (i.e., reported mean scores on a certain standardized test) using the metafor package in R. ...
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Confidence intervals and bonferroni correction

Currently I'm thinking about using confidence intervals to compare the difference in means between a few groups. However, if I understand correctly I need to use the Bonferroni correction if I test ...
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How do I compute a Cohen's d from b weight and standard error?

From Table 3 and the paragraph below, you have a good deal of the information I have available. N's for taser and non-taser conditions are 339 each. My initial inclination is to take the raw B weight ...
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Power Calculations for 3 arm clustered randomised trial

I need to do power calculations for a 3 arm trial (to determine minimum detectable effect size, given the alpha, power, sample size etc). I found the R package Three.Arm.Trials, however I was ...
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Effect size for a trial with pre and post measurements

I have recently been told two different ways to prepare data for calculating effect size (Hedge's g) of a placebo-controlled trial: use post-intervention means of the assessment values for both ...
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Investigate impact of one variable in the present of another

In my project analysis, I am currently investigate the impact of the ambient temperature on vitamin D level. I am using parametric tests as I transformed the Vit D data to meet the assumption of ...
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How to handle studies that don’t provide an estimate of effect size in a meta-analysis?

Say we want to survey the literature to find out the effect of Treatment A on Value B. Some studies provide an effect size estimate with confidence intervals and t-test results (e.g., “Treatment A ...
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Calculating effect sizes in single participant case study research papers

Hoping I can find some help. I'm writing the methods section to a systematic review and I want to mention my approach to comparing Treatment Outcomes and Clinical Efficacy. The title of the ...
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GLM - sample size estimation for given power and effect size and data set

I am working with R's car package highway1 and calculating a general linear model with rate as the dependant var (metric) and acpt as the independant var (metric). Additionally i used htype (...
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What's the difference between using a composite null and running a power calculation for minimal effect size?

Probably a weird place to quote, but I just stumbled across this discussion on Reddit, and one of them said (with typos fixed): The effect size in a power calculation has no relationship whatsoever ...
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Effect size in linear mixed models

Thank you for reading this question. I know there have been a few discussions regarding this topic, but I couldn't get a satisfactory answer. So here is my question, with some details in the ...
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What's the statistical method of comparing the amount of pre-post difference scores of between groups?

I am currentnly doing a meta-analysis of the effects of social cognitive training on social cognitive function of patients of schizophrenia. There are wo conditions: treatment group receving social ...
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SMD meta-analysis including cluster-randomised trials: is it possible? If so, how?

Where we have cluster-adjusted results from trials (summary statistics), under what circumstances can we include them in a standardised mean difference (SMD) meta-analysis and which calculations are ...
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Effect size calculation for Kruskal-Wallis mean rank test

I have a published paper in which I'm attempting to calculate the effect sizes for various outcomes. For a pre-post scale, the authors report the sample size, mean rank, and p-value for an outcome (...
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Checking association between each category of a variable and disease outcome

Suppose a disease can have four different outcomes: Normal, disease_status_1, disease_status_2, and disease_status_3. Let I have two categorical variables in the model: sex (male or female) and age (&...
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Anticipated effect-size confidence-interval range, as alternative to power calculation?

To determine sensible sample sizes prior to data collection, we typically calculate power, that is, the probability that we will "detect" an effect with such and such an effect size. I would rather ...
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conducting a meta-analysis on pre-post control design studies that use count data

I would like to conduct a meta-analysis on a set of studies that have measured an outcome over a period prior to intervention and post-intervention for a control group and experimental group. A method ...
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Effect size for mixed ANOVA

I have a mixed anova with repeated measures design: two between-subjects factors, doctor (3 levels) and method (3 levels), and one within-subject factor, time (1w, 3w, 2m, and 6m). 3 doctors would be ...
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Measuring predictive accuracy of an ordinal outcome when the predictor is continuous

I'm predicting a response measured by a 5-point likert scale from a model that produces continuous predictions of the same variable. For example: ...
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1answer
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What is the relation between the effect size and correlation?

Correlation refers to the degree to which a pair of variables is linearly related. The effect size quantifies some difference between two groups (e.g. the difference between the means of two datasets)....
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Slope as measure of effect size (via standardised correlation coefficient)

Does the situation below correspond to similar or to different effect sizes? The (standardised) Pearson correlation coefficient should only depend on the cumulated distances between data points and ...
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Have I calculated my estimated sample size correctly?

I am conducting a study to answer the following question: In women with type 1 or type 2 diabetes in pregnancy, is there a difference in glycated hemoglobin A1C level between women who have a high ...
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Is it possible to meta-analyze means on different scales?

I have study-level means/SDs reflecting depression symptom severity from multiple single-group studies. I do not have access to participant-level data. The studies all use different measures, and I ...
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101 views

Cohens d from Mixed method model - for the interaction term

I am doing a mixed method model: m1 <- lmer(DV ~ IV*Country + (1+IV:Country|Region), data = data) I am using the lme.dscore to get the Cohen's d for the model....
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Convert ratios into a standardized effect like Cohen's d

This is my first time working with log data. I have performed a contrast of the difference between two log means and have back-transformed this to give me a ratio of geometric means. I'd like to ...
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Measuring effects of IV (constant) on DV

I have an independent variable (a bias) that is technically a constant. I want to measure the effects of the IV on the DV. How do I do this? I'm using SPSS. Let's say, participants produced A or B ...
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What test to use to compare two proportions (and calculate effect size and confidence interval)?

There are many related questions here and elsewhere, but I found no satisfying answer. There are plenty of related tests and concepts: Z-test, chi-squared test, G-test, McNemar's test, Fisher's exact,...
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error residual identical for within subject ANOVA and between subject ANOVA with double the sample size

I noticed something interesting while playing around with data. If I conduct a 2-by-2 within subject ANOVA with 20 subjects my sum of square residuals look like this: ...
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Before/After unpaired study with control villages analysed in R

For the implementation of a project, we have been following household access to services in two groups of villages, one an intervention group (I) and one a control group (C). Access as a Yes/No ...
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Calculating effect size for a study with no groups

I am working on a meta analyisis of the effects of e-learning in an organizational context. I have prepared a list of about 25 studies to analyze and I have organized all the path coefficients based ...
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Significance of effect size less then estimated by power

Suppose I estimate a sample size needed for a hypothesis test of proportion difference, using a binomial distributional assumption, with power 80% and effect size 25%. Then I perform an A/B ...
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Meta-analysis for case control studies

I am working on a method of meta-analysis for case-control studies by stratifying cases and controls then calculating the effect size. Can I do a meta-analysis including only case-control studies for ...
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Cohen's d and the use of the standard deviation of the control group

In this paper Cumming, G. (2014). The new statistics: Why and how. Psychological science, 25(1), 7-29. one can read this about Cohens' d: For two independent groups, if we assume homogeneity of ...
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Resource for an explanation of Sample size calculation when $\alpha$, Power and Effect Size for t-Test are given

For a simple z-Test or t-Test (one-sample or two-independent-sample with $n_1 = n_2$ and equal variance) I want to calculate the required sample size $n$ when the significance level $\alpha$, power ...
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How to interpret contradicting path coefficients and f² effect sizes in Structural Equation Models (SEM)?

In the evaluation of my structural equation model with the PLS-SEM approach I have path coefficients between two constructs that are significant (p-value < 0.000) but the effect size f² is small ...
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Standard error for difference between two independent gains

I've calculated an effect size for the difference between two standardized pre-post differences of two independent groups of subjects. That is: $[Mean_{dif_{group~1}}/SD_{dif_{group~1}}]-[Mean_{dif_{...
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How does variation in the effect size affects power?

Effect size The effect size affect the power of a statistical test. We typically summarizes the magnitude of the effect of a variable as a single number (which we call the effect size). To my ...
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Inflation of effect size estimation among significant results?

Correction for multiple testing is often performed on the alpha value. However, multiple testing is, I think, likely to inflate also the estimated effect size of the most significant effects found. ...
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Conclusions from combination of P value and Effect size

Limitations of P values are being increasingly highlighted in recent literature (e.g. here and here). To evaluate results of unpaired t-test, following is an approach combining P values and effect ...
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Bayesian method to determine effect size

I have data on heights of 2 groups of persons. Usually Cohen's-d is used to determine effect size. Is there any Bayesian equivalent of Cohen's-d which reflects effect size of the difference between ...
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variance of Cohen's d effect size for two “dependent” samples [duplicate]

The derivation of the sampling variance of Cohen's $d$ effect size for the case of two independent samples is well established (see HERE). However, my question is what is the sampling variance of ...
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Hypothesis testing on two disproportionate samples

I want to conduct hypothesis testing on conversion rate of two disproportionate samples. One contains 20k Data points and other contains 180k datapoints. How can I do a hypothesis testing on such ...
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Interpretation of two odds ratios derived from two different cohen's ds, comparability for meta-analysis?

I have a question regarding the conversion of cohen's d into odds ratio (OR) and the comparability of results from two different situations. I wonder if the ORs derived from the two situations can ...
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Why is my p-value correlated to difference between means in two sample tests?

A colleague has recently made the claim that a large p-value was not more support for the null hypothesis than a low one. Of course, this is also what I learned (uniform distribution under the null ...
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Comparing means in large samples: effect size and p-value

I have a large sample (10000+ per location) of temperature measurements which I would like to compare between 3 locations. I'm checking if there is a significant difference in temperture means between ...