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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Does the Vargha-Delaney A effect size stand as a standardized effect size?

Effect sizes are categorized into 'Standardized effect sizes' and 'Unstandardized effect sizes'. My question is, Vargha-Delaney A falls in which of the categorizes? does it cound as standardized ...
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Use Effect Size VS p-Value when determining the best fitting distribution?

I have a large sample size of about 50,000 I want to determine what theoretical distribution fits the distribution of my samples the best. What I did is to fit all distributions I know to the data ...
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Meta - Analysis - Effect size calculation

I am trying to include a study into my meta-analysis, that reports results of an ANOVA: F(1,76) = 11.23, p = 0.001, n²=0,13 My question is how to calculate Hedge g from this data? I work with R, using ...
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How do we test if Something is an “Actual Phenomenon” [on hold]

I have been reading about claims that people experience "Existential Ennui". Many claim there is no such thing. I am just curious on what techniques one may use as a means of testing whether this, or ...
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Cohen's d in split-plot experiments

There is some demand for effect-size measures in doing post hoc analyses, and I am trying to decide whether to provide for this or not in an R package of mine. If I do, I would concentrate on Cohen's $...
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Effect size for meta-analysis from ANOVA with significant interaction term

For a meta-analysis, I found a study in which the main effect of A on my dependant variable was not significant but the interaction of A and B and the interaction of A, B and C were. I also have only ...
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Calculating $\eta^2$ for a repeated-measures ANOVA - What goes into the denominator?

I need to calculate $\eta^2$ as the effect size for a 2 x 2 repeated measures ANOVA as part of my PhD, but I am confused as to whether the intercept and its error term from the between-subjects ...
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Is there a distinction between the “squared semi-partial correlation” and the “semi-partial R squared” of a fixed predictor?

The package 'r2glmm' in R calculated the "semi-partial R squared" of each fixed predictor in a mixed effects model. The package describes this as "The semi-partial R squared statistic corresponds ...
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Effect size to minimum detectable effect

I am running an A/B test for differences in customer revenue. More specifically, a t-test for the mean customer spend in my A and B groups. Before I launch my test, I would like to run an analysis ...
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Can I use partial eta and/or partial omega squared for effect size estimation of each independent variable in linear mixed model regression?

I need to estimate effect size estimation of each independent variable in linear mixed model regression. Here is a code: ...
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21 views

Effect size measure for pretest-posttest design

I recently conducted an intervention study with random assignment to treatment and control conditions. Participants completed a pretest before the intervention and a posttest after. I analyzed test ...
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Confidence intervals for effect size do not match using the packages esc and meta

I obtained different CI for Hedges g using the package esc and meta. ...
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How to calculate an effect size for chi-square in R

For the life of me I cannot figure out how to do something that should be so simple. I have found http://www.real-statistics.com/chi-square-and-f-distributions/effect-size-chi-square/ but it gives no ...
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Teaching students about non-significant results and large effect size

This year I am going to teach statistics to sophomore year students of psychology. We'll be training such methods as one-way ANOVA. The example will be the time-reaction of a cognitive task among ...
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Compute effect size from simulated NULL distribution

I computed a empirical p-value (permutation test) where I compare my real value to simulated values (N=100,000). In the end I've a distribution like this (vertical line = my real value). For the p-...
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Correcting for resample-unique correlations when bootstrapping CI's for contrast scores

I would like to bootstrap myself some confidence intervals for the standardized effect sizes of a simple within-subjects design where the same variable was measured on two occasions. For this I am ...
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Correcting for reliability scores for Hedges g

I've received a revise and resubmit on my meta-analysis investigating the effects of a positive psychology intervention on depression and anxiety symptoms. I used Hedges' g as the effect size within a ...
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Summary effect size of multiple dependent effect sizes

Problem Statement I am currently conducting a meta-analysis. At the moment, I am just calculating the effect size for each included study (for our purpose we chose the correlation coefficient r). ...
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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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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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42 views

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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54 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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73 views

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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127 views

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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1answer
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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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1answer
167 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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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 ...