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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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getting insignificant p-values but large effect size what should I do?

I used Qualtrics to conduct a survey and received 700+ responses. I also collected demographic data to disaggregate the data and observe any differences between groups. A couple questions used display ...
neybeh's user avatar
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R: How to calculate power to detect a change in mean beta reg.?

I'm interested in calculating the power to detect a change in my mean response variable by a certain effect size, but I'm not sure how to start. My Y variable is mean plant cover 0-100% cover (mean of ...
Nate's user avatar
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meta question: Understanding correlation vs. effect size

For some context: I've been looking at some meta-analyses on factors that explain happiness (well-being), because I wanted to check the happiness-claim of a certain philosophy and want to be happy in ...
CrossVal_Asker's user avatar
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Effect-Size Analysis: Cohen's D, Pearson's r, or something else?

I am trying to do an effect-size analysis on dam release's effects on downstream temperature. I have a large dataset of data loggers taking temperature readings at various sites downstream from the ...
Matt Schaaf's user avatar
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Quantifying effect-size and correlation between two data frames

I am conducting an effect-size analysis on dam release and downstream temperature measurments. To do this, I am comparing the gauge temperature (the temperature of the water released from the dam) ...
Matt Schaaf's user avatar
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Is this the correct way to go about determining correlation between upstream and downstream temperature?

I am new to stats and R in general, so please bear with me. I have been trying to find an answer to this question for about the past week and have spent a ton of hours researching but am still ...
Matt Schaaf's user avatar
1 vote
1 answer
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Two-Way repeated measures ANOVA with multiple data points per measurement

I would like to perform a study with physicians of three levels of experience. They shall perform a task under three different conditions. For each condition, the task is performed multiple times (e.g....
Hiddigei's user avatar
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Why can we use RMSE as a proxy for the effect size of a VAR or Granger Causality?

My question here follows a previous question by me here: Is there a meaningful option to compute something like an effect size for Granger Causality?. In this previous question I asked for options to ...
Philipp's user avatar
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Is there a meaningful option to compute something like an effect size for Granger Causality?

I am running Granger Causality (GC) analysis using statsmodels.tsa.stattools.grangercausalitytests between several time-series pairs. The time-series pairs used for ...
Philipp's user avatar
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3 votes
1 answer
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How do you interpret estimates when the model is the same for two exposure variables?

I want to investigate the direct effect of two environmental variables $X_1$ and $X_2$ on a quantity $Y$. $X_1$ and $X_2$ are connected together and with two other environmental variables $X_3$ and $...
Boussens-Dumon Grégoire's user avatar
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Pooled Hazard Ratio or Crude events (M-H to RR or OR) for mortality outcomes in Meta-Analysis?

I'm performing a MA to estimate the effect of treatment A respect to Placebo (or propensity-matched control group) respect to all-cause death. All the studies included in my MA report both crude ...
Michele Maremmani's user avatar
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Is it possible to calculate effect size from the relative pre-post change?

I am trying to conduct a meta-analysis that focuses on the pre-post change of an intervention. While most studies reported the pre and post mean and SD scores of the outcome, some only reported the ...
Allie's user avatar
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1 answer
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Effect size/power analysis of categorical variable in multilevel model

How to decide the effect size of a categorical variable with multiple levels (e.g., three or four) in MLM? And how to calculate the power of such variables using a simulation (or other) approach?
Misaya's user avatar
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Interpreting the result of post hoc power calculation with powerCT.default for proportinal hazards model

I have 2 samples of data both with over 800000 instances. . In both samples, ~ 75% of people have the exposure. In the first sample 0.3 % of people have an outcome and in the second 5% have an outcome....
Milo's user avatar
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Sample size calculation for prevalence studies: how do I find d when reviewing a published study?

I have found the following formula in Munn et al.: $$N = \frac{Z^2 P(1-P)}{d^2}$$ $N$ = sample size $Z$ = statistic for a level of confidence $P$ = expected prevalence $d$ = precision The problem I ...
Fabio Carraturo's user avatar
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How can I convert effect estimates to be on the same scale? [closed]

I am doing a meta-analysis of studies that examine the effect of air pollution (continuous exposure) on a health outcome. Many of the studies report effect estimates for different units of exposure. ...
embracent's user avatar
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Is the post-hoc observed effect size redundant with the p-value, just like post-hoc observed power is?

Assume for simplicity sake that we are running a 2-sample t-test on 2 normally distributed populations, from which we collect 2 i.i.d samples. (for a start; we can expand later to more complex cases). ...
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Effect size calculation (with CI) for proportions with a 2-arm pre-post design (i.e. experimental and control group)

I've been trying to find how to work out the effect size of an intervention that has only provided information on the proportion of participants who reported they had increased 'knowledge' after the ...
CML's user avatar
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How do I quantify the effect of a factor with many levels?

I want to look at the effect of brood ID on fledging success (a binary variable) in a sample of wild birds. Brood ID has ~150 levels. I have performed a likelihood ratio test comparing two logistic ...
Emadeel's user avatar
4 votes
3 answers
278 views

Cohen's d or Cohen's d-like effect size estimate for regression slope?

Can Cohen's d be calculated for the linear regression coefficient associated with a continuous predictor? If so, what is the formula? I found one question asking this already, with an answer ...
Evan's user avatar
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Establishing the Smallest Effect Size of Interest (SESOI)

In my experiment design, I will be testing subjects multiple times under two conditions: in a controlled lab setting and in real-life situations. Testing subjects repeatedly is necessary as ...
Simen Leithe Tajet's user avatar
1 vote
0 answers
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Can p-values from permutation tests be interpreted as a measure of effect size between group?

I'm conducting a research project involving gene expression analysis. We've developed a method to calculate a score from a given set of genes, A. To evaluate the ...
zhang's user avatar
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Effect Size of CLMM

I am conducting an omnibus analysis of a CLMM model from the ordinal package. I passed the CLMM model to the function ...
Tavaro Evanis's user avatar
3 votes
1 answer
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Completely standardized indirect effect (Preacher & Kelley, 2011) in lavaan

Preacher & Kelley (2011) have proposed an effect size (i.e., completely standardized indirect effect) that quantifies the magnitude of an indirect effect. My question is whether lavaan's ...
Matthias's user avatar
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Effect size with GLMM gamma distribution

In response to a previous question posed about effect sizes with a generalized linear mixed model with a binomial distribution, it's been clarified that estimating effect sizes is not straightforward. ...
kfin's user avatar
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What is a good measure of the effect size of group difference in a multigroup multilevel model?

Consider that you have a multilevel model measuring students' mathematics knowledge. The students are nested within classes, and classes are nested within schools. Additionally, we want to examine the ...
J. Doe's user avatar
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Validity of calculating Cohen's d from t-score in longitudinal linear mixed-models

I'm analysing some data from a pilot study using longitudinal linear mixed models. Because of conventions in psychology it's common to report effect-size in Cohen's $d$ for interpretability. I found ...
Vilgot Huhn's user avatar
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How can I normalize Hedges' g from two extreme conditions around the control condition?

The variables I am discussing below are not the ones I am actually using but I think that they should give a better sense of what I am trying achieve. I am performing a meta-analysis of some chosen ...
aria's user avatar
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1 answer
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Is there a convention to denote effect size (like 1-3 stars for statistical significance)?

The convention of using stars to denote statistical significance is widely known, so one star means p < 0.05, two stars p < 0.01 and three stars p < 0.001. Nevertheless, statistical ...
Maciek's user avatar
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Sample Size impact on Effect size

I have a small sample size ($n = 23$) and I ran some t-tests to see if there were any group differences (group one had $11$ participants and group two had $12$ participants). I can wrap my head around ...
Louis's user avatar
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Effect size + variance calculation single group pretest posttest - different sample size pretest-posttest

I include single group pretest-posttest study designs in my meta-analysis. I calculate the effect size as follows: difference between posttest mean and pretest mean divided by the standard deviation ...
FZZ's user avatar
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1 vote
0 answers
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How do I calculate effect size in a pretest-posttest three group randomized study for two planned contrasts (ANCOVA)?

I am having a hard time calculating the individual effect sizes for ANCOVA simple contrasts ($1$ vs. $2$ and $1$ vs. $3$) in a randomized pretest-posttest design study with three groups. In the ANCOVA,...
Eniko's user avatar
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2 votes
4 answers
83 views

How can power and effect size help me interpret my A/B test results?

To give an idea of my use case, I'm performing an A/B test using a two-sample t-test to compare the mean between a control and a treatment sample. I set $\alpha=0.05$. I set my effect size $d=0.01$ ...
KiwiKiwi's user avatar
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44 views

Meta-analysis: estimating partial correlation coefficients using estimates from multi-level analyses

I would be very grateful if someone could offer some ideas or point to relevant literature on the calculation of partial correlation coefficients (PCCs) using estimates from multi-level analyses. ...
Mugen's user avatar
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Converting from Chi Square to Hedges in the context of mixed effects model comparisons

I'm attempting to extract a Hedges' G effect size from a publication that reports the chi square statistic (and degrees of freedom) derived from comparing two mixed effects models: the first model ...
Victor Pokorny's user avatar
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38 views

Calculate sample size from simulated results

I have a dataset of multiple purchases of the same product from a group of individuals. I aim to simulate the impact of increasing the pricing if the quantity of the purchased product by customers ...
VDC's user avatar
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1 vote
1 answer
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Interpreting effect size for partial eta squared: how do I interpret the recommended values for small, medium, and large?

I am using partial eta squared to calculate effect sizes for ANOVAs and Aligned-rank transformation (ART) tests. I understand that the recommended values to interpret the results are small (0.01), ...
Morgan Ferrell's user avatar
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13 views

Effect size output of ANOVA obtained from anova_stats is different from effectsize::eta_squared

I ran an ANOVA using aov in R. Then I used both effectsize::eta_squared as well as ...
Vipin Verma's user avatar
6 votes
2 answers
350 views

Using a t-test to test effect size

In my line of work, I work with large data and often run stat tests to compare differences between groups. The problem I am facing is that if I use a $t$-test to measure any difference, the result ...
baz's user avatar
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2 votes
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Computing Bayes Factors for pairwise comparisons, linear mixed models

A reviewer asked for either Bayes Factors or effect sizes for pairwise, planned comparisons in linear mixed modeling. In the experimental design, I have 30 participants, one fixed factor (repeated ...
Elizabeth's user avatar
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2 votes
1 answer
173 views

Help understanding Cohen's D for pairwise comparisons in lme

I've been asked by a reviewer to provide effect sizes for pairwise, planned comparisons. In the experimental design, I have one fixed factor with three conditions (Consistency). Passage & Subject ...
Elizabeth's user avatar
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0 answers
35 views

Help with effect sizes in lme4

I want to compute an effect size for a fixed factor. In this study, there is one fixed factor with 3 conditions (Consistency). Passage and Subject are random effects. I used a Cohen's d to compute ...
Elizabeth's user avatar
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1 vote
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what ES should i use for a multilevel meta-analysis (metafor package) of pre-post studies with intervention and control group?

We've done a systematic review of studies that investigate the effect of physical exercise on pain and disability in workers, and we've been asked to complement it with a meta-analysis of the data. So,...
Francesco Favro's user avatar
3 votes
2 answers
125 views

Remove effect of an independent variable on a dependent one

Currently, we are taking weight measures from a brick with a weight of 1kg as a way of calibration. However, the final weight returned by the sensor is not 1kg, instead, it varies along with ambient ...
anttphy's user avatar
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1 vote
1 answer
51 views

How is the critical value calculated in rpact package?

A critical value (treatment effect scale) is output as 0.127 from R code: ...
Stat_Stat's user avatar
2 votes
1 answer
62 views

What references assert that the effect size of a nonsignificant covariate may be high?

An answer to a FAQ notes: The effect size of a covariate may be high, even if it is not significant. Does anyone know of papers I can reference to support that assertion? FWIW, I do understand why ...
Mohan's user avatar
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1 vote
1 answer
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Sample Size Calculation for Gene and Protein Biomarker Study

The PIs are looking for biomarkers in pre and post-trauma individuals. I need to calculate a sample size for a microarray study of 10 genes and the top 5 up- and down-regulated proteins and ...
Tavaro Evanis's user avatar
5 votes
1 answer
178 views

What references discuss the problems with phi as an association measure?

(Olivier (2013) states that many have pointed out problems with $\phi$ as an association measure and advocate the use of odds ratios as an alternative Unfortunately, it does not give citations for ...
Mohan's user avatar
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7 votes
2 answers
445 views

What does reported "r" mean in the context of a t-test?

In a psychological paper (Fujita et al., 2006), the authors perform a two sample t-test for independent means. They report the following values: $M_1$ = 9.88, $M_2$ = 8.47, t(66) = 2.25, p = 0.03, $p_{...
uke's user avatar
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2 votes
1 answer
81 views

How to calculate mean difference for effect size calculation?

For a two-sample effect size calculation on paired data (or a one-sample test on differences), does it make sense for an effect size to be negative for a hypothetical % increase of a mean? I’m doing a ...
Nate's user avatar
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