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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Computing effect size (d) for lmer() in R
I have selected to compute the Cohen's d effect size for the fixed effects of my linear mixed model. However, it's a little unclear why I'm getting the results I am. First, I am using the method ...
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Derivative-based effect size for Gaussian GAMs
It is often the realistic advice I have seen here that Gaussian GAMs are not regressions with which you can easily approximate an effect size for, as the effects are of course non-linear. However, we ...
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Ratio of odds ratio to Cohen d
If I have two binary predictors and a binary response how can we calculate the effect size of the interaction term. I use logistic regression from statsmodels package in python.
Will it be ratio of ...
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Is it possible to perform a meta-analysis of multiple outcomes and multiple predictors?
I have a pool of 20-ish quantitative studies that report odds ratios for a particular outcome (e.g. homelessness) but most studies will also report a few more outcomes. All of these studies report the ...
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Wilcoxon test for mixed data
I have gameplay data of 20 patients, some is following normal distribution and some is following non normal distribution, so I used Wilcoxon test to identify if there is significant change in speed in ...
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Multiple group analysis in canonical correlation analysis
Canonical correlation analysis estimates the relationship between two canonical sets of variables. However, I am interested in using a technique to compare these CCA results across groups (something ...
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Can I create effect sizes from published reports without access to the data? Thinking about standardizing unstandardized coefficients?
I'm reviewing and synthesizing 48 published articles on the same topic (association between x and y). Instead of describing findings based on statistical significance and power, I'd like to be able to ...
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How to measure the increase in violent crime between years?
I have crime data from my country, consisting of the counts of recorded crimes (split by various categories), as well as population data from census years. I want to measure if there has been a ...
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Effect size in multiple logistic regression
I have one dummy independent variable, one categorical independent variable with six categories, and two continuous independent variables. The dependent variable is binary (yes/no). The interaction ...
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Computing the effect size of a Level 2 predictor in HLM
I am looking for advice on computing effect sizes for Level 2 predictors in HLM models.
I found this documentation: https://ssicentral.com/wp-content/uploads/2020/07/FAQ_Effect_sizes.pdf, but am ...
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calculate effect size from regression table
I am working on power analysis for a project. I want to benchmark effect size from another study. How can I find the effect size (Cohen's d) just by looking at the regression table below? For instance,...
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Effect-size of a fractional factorial design?
Let us assume I conduct an experiment, in which the participants perform four different tasks, getting a tool support or not. We measure the time to complete each task, either with the support of a ...
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Improve estimation of effect-size (difference between two distributions) by using LDA distance to decision boundary
Before getting to the point, I will provide some context:
I have a dataset that includes $176$ quantitative neuroimaging markers ($m_i$ for $i=1,...,176$) and several categorical variables ...
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How to transform GEE coefficients to Cohen's d (standardized mean difference) for meta-analysis
I am conducting a meta analysis and am looking into how to convert coefficients (with SEs) from a GEE linear estimation into a standardized mean difference, Cohen's d. Does anyone have any hints on ...
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Determining the effect of two coefficients combined when the model includes an interaction term
Imagine I'm trying to model traffic stops with a logistic regression.
...
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Calculation of standard deviation of the mean changes from the p-value or z-value of the Wilcoxon test
I am conducting a meta-analysis of observational studies without a control group that compared a parameter's value before and after an operation. All included studies have reported their results as ...
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Is the mean difference between two groups a relative treatment effect?
In randomized trials, I know that treatment effects such as the odds ratios, relative risks and hazard ratios are considered relative treatment effects.
What about the following effect sizes?
a. Mean ...
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Is the Neyman-Pearson paradigm for hypothesis testing adequate in the social sciences, and if not, is calculating a priori power still adequate?
I'm reading about Fisherian vs. Neyman-Pearson paradigms relative to hypothesis/significance testing. (NB: I'm new to this and self-studying it, so I'd be glad to be corrected if I misinterpret ...
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G*Power ANOVA repeated measures within-between interaction
I'd love to get a sanity check on a sample size calculation I'm running in G*Power. I'm planning a study with 2 groups and 2 measurement points, aiming for a f of 0.10 because, to my understanding, it'...
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Computing Cohen's D directly from a Welch's t statistic
I'm performing a meta-analysis and am trying to extract a Cohen's $\hat{d}$ effect size measure from a paper; however the paper does not report any means or SDs. They do, however, report the results ...
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How can I directly compare the effects of a predictor on a continuous and a dichotomous dependent variable?
I want to assess how a predictor differs in its associations with 2 different dependent measures (i.e., a continuous measure of objective memory and a categorical measure of self-rated memory). I also ...
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How to calculate effect size to to use Power Analysis to get minimum sample size when standard deviation is not available (digital marketing AB test)?
TLDR: I can't find a way to calculate the effect size needed to be inputted to Power Analysis to get the minimum sample size needed to 90% statistical significance as I can't calculate standard ...
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How to calculate the effect sizes for a meta-analysis if a RCT study reported the correlation coefficient using partial pearson corrleation analysis?
I am currently performing a meta-analysis focusing on investigating the changes in variable A following weight loss. To address this, I have included studies that provide pre-and post-intervention A ...
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Intrasubject coefficient of variation for cross-over sample size calculation
I would like to calculate the required sample size for a crossover design based on a study conducted in a parallel-design. I understand that one needs the within subject CV. Unfortunately, the authors ...
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General interpretations of permutation null distributions under the alternative
I've come across some papers employing z-scores of permutation null distributions as a primary metric in neuroscience (for an example, see here).
The authors computed a coefficient of interest in a ...
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How to calculate effect size based on percentage and sample size?
In an intervention study, I have the following information - % of students passing an exam pre- and post intervention, sample size for control group and intervention group at pre- and post ...
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How to translate calculated Effect size into original units of measurement?
I am running a hypothesis test, and I am trying to share the statistics on this test to business user. I have calculated effect size using Cohen's d. Now I want to find a way to convert this effect ...
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How to account for difference in group sizes for logistic regression
Using this study as an example, I am wondering if the size of different study groups run in the same models impacts the conclusions we can draw from statistical tests.
In this study, the researchers ...
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meta-analysis when the control value is taken from a standard (iso, en, etc...) and do has not any variance
I am starting to conduct a meta-analysis on the effect of different raw materials on pellets quality (for bioenergy purposes) I have already the database of studies and my idea initially was to ...
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How to find Cohen's f for multiple regression with interaction included?
I am currently investigating the moderating role of mindfulness in the association between academic distress and suicide ideation with depression as a control variable. I finished doing the multiple ...
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Conducting power analysis to minimize number of tests: generalized linear model (GLZ) with binary outcome, zero inflated binomial predictors R
My problem: I have a fixed, imbalanced, case-control cohort where I am using two (2) low occurrence predictors (rare variants) to try to find an association between the predictors and disease. I will ...
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Statistical power of an experiment calculation
As titled,I had some confusion related to statistical power calculation.
The calculation is done using
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Convert Cohen's d to nonparametric effect size and use as equivalence bounds
In a within-subjects design (n = 30), I had planned to run equivalence tests with the equivalence bounds set at the effect size of Cohen's d 0.35. This is partly based on previous research and partly ...
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Why is it important to correct for correlated (dependent) measures when reporting Cohen's d?
I am calculating within-group effect sizes from pre-test to post-test. Cohen's dav reports this effect size as a proportion of the average standard deviation (Lakens, 2013):
Meanwhile, Cohen's drm ...
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Determine the sample size to validate a bug fix
Using gpower, I would like to calculate the sample size to validate a bug fix.
There is a software bug that appears in 3 out of 1000 test runs.
I would like to validate a bug fix so that it doesn't ...
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Pairwise Effect size for Dunns Test
I am using ggsttaplot - I am curious how to get effect size for each pair:
...
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How to calculate effect size of moderation analyses on repeated-measures data?
I conducted a moderation analysis on repeated-measures data using the MEMORE macro for SPSS (https://www.akmontoya.com/spss-and-sas-macros). However, I need standardized effect sizes but I haven't ...
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Effect size for comparing two models using anova(test="Chisq") function in R
How do I get the effect size (e.g., Cohen's w) for a comparison of two models using anova(lm.1,lm.2,test="Chisq") function in ...
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Can high standard deviations explain my non-significant & low effect size results? (please read description)
I'm trying to analyse bullying experiences across three age groups. The DV is scored on a 5-point Likert, and the IV is categorical (ages 11, 13, and 15).
Initially I ran an ANOVA to see if there was ...
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Glass' delta effect size when there is no control or pre-measurement group
Cohen's d and Hedges'g effect sizes are used when two distributions have equal variances, which is a requirement and assumption to use these statistical tests.
When two distributions have unequal ...
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One Sample Wilcoxon effect size
I am struggling with effect size calculations for the Wilcoxon test for one sample in R.
My data:
item1 <- c(1,5,3,4,4,2,3,2,1,4,5,4,3,1)
...
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Calculate effect size Cohen's w (omega) for a chi-square test in model comparison
I have two logistic mixed-effects models, nested within each other and differing in only one fixed variable:
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compute expected effect size from n
In most scenarios power calculations are used to determine n, given expected effect size, power and significance level. However, if I already know ...
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Is post-hoc power analysis redundant too in the case of a *significant* result? [duplicate]
I've read that post-hoc power analysis is useless when the result of a test is statistically insignificant, which I understand (post-hoc power analysis is just circular logic in this scenario). But ...
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Is there a statistical approach to determine the minimum sample size for comparison of sums over time?
I have the number of items sold of various products over time from a supermarket. Each product belongs to a category of products. Some categories have a large number of items sold and some categories ...
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Standardized dependent variable, effect size interpretation
I have the following model:
RT ~ condition + (1|participant)
RT is a continuous variable. Condition has three levels and is coded using Helmert contrasts.
I ...
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Can you explain me how critical value can be included in this equation of the minimum detectable size?
According to the theory, power is 1-beta which is the probability of not rejecting the null hypothesis when this one is false. Then power uses the alternative hypothesis distribution.
The minimum ...
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Sample size and power analysis: Chi-square
Can someone help with a sample size analysis question?
Study design:
I have a sample randomly assigned to answer 1 of 5 different questions that vary in difficulty (1 - Easy -> 5 - Hard). The ...
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Can I calculate the correlation coefficient from the beta of fixed effects in a linear mixed model?
I would like to determine a partial correlation from fixed effects in my linear mixed models.
If i would run a model for example $Aij = \beta_0 + \beta_1X + \beta_2Y + \beta_2Z + ui$ + ϵij
Can I ...
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How to determine effect size confidence interval in a difference-of-differences A/B test
This seems like it should be a really simple thing, so I apologize if this has been answered elsewhere, but I've browsed dozens of existing questions and none seem to fit exactly.
Suppose I have two ...
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