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

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Is there any possible method to calculate effect size in SPSS mixed model?

I run MIXED command for mixed model analysis of repeated measured data. However, there is no option or menu for estimate power(like partial eta in GLM) in mixed analysis. Is there any method to ...
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24 views

Multiple Regression - effect size

I want to calculate the effect size of a multiple regression. So far, I used Cohens f^2. Somehow, I wonder, if the effect size expressed by Cohens f^2 is an appropriate measurement. Let's assume ...
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110 views

How to test difference between standardized difference between means

On a data set I inherited, I calculated the standardized difference between the means of 2 groups, d, for each of 5 variables. All the data was collected from same set of about 175 people, with 35 in ...
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22 views

meta-analysis, effect sizes for standard deviations

Is there any possibility to calculate effect sizes for the differences of standard deviations of two groups? (Is there any possibility to calculate the difference in the standard deviation between two ...
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32 views

Can I calculate effect size using only % difference between means?

I need to calculate the effect size of a published experiment so that I can compare it to a replication attempt. However I have very limited information about the original experiment - only the mean ...
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42 views

When an effect size has to be considered sufficiently large?

I submitted a paper in which I analyzed the data by a mixed design ANOVA. I reported generalized eta squared as effect size. After significant interactions, I conducted planned comparisons. A reviewer ...
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11 views

Mixing ITT and TOT/LATE Effect Sizes in Meta-Analysis

I have a question concerning the coding of Effect Sizes for a large (educational) Meta Analysis with mostly latent outcome variables. Some studies provide "Intent to Treat" Data from which I ...
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1answer
25 views

Compare two distributions of large sizes and unequal variances where one distribution is heavily skewed

My data is from cells that are treated under two different conditions and then their response to the condition is measured by one output variable. The cell populations in the two conditions are quite ...
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11 views

Compute effect size based on simulation using different lists of different length

For my research purpose I wrote a small simulation to compute an empirial p-value based on an input gene list and a reference gene list. The idea is to check for each gene in the input gene list, the ...
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33 views

Definition of $\lambda^2$ effect size measure

In an article in the American Psychologist there is a series of bar graphs with a statistic next each bar. The statistic is described in the text and in the graph captions as being an effect-size ...
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1answer
159 views

Mann-Whitney U-test: confidence interval for effect size

According to Fritz, Morris, and Richler (2011; see below), $r$ can be calculated as an effect size for the Mann-Whitney U-test using the formula $$ r = \frac{z}{\sqrt N} $$ This is convenient to me, ...
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29 views

How do I convert Cramer's V to Cohen's d?

Say I have a chi-squared test that compares 3 different groups: $\chi^2_2 = 9.81$, $p=.012$, Cramer's $V=.33$ How would I go about converting this to a $d$-statistic? Is the proper approach in ...
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22 views

Can Hedges' d be used to compare unlike effects?

I've got a question related to the use of Hedges' d in a meta-analysis of insect fitness information. Here is a link (pdf) to the paper I'm working with. In the appendices, the fitness information ...
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14 views

Effect size for hypergeometric test

Given an urn with N genes, ugh - I mean with N balls, B of which are white, I can calculate the probability of randomly drawing b or more white balls in a sample of n using hypergeometric test. This ...
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1answer
17 views

problem: a sample size for the assumed effect in the 2 sample proportion test

I would like to calculate a sample size for the 2 sample proportion test when the significance level is assumed (0.05), power is assumed (0.90) and I'd like 2 sample proportion test to detect that ...
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21 views

Non-parametric effect size

Effect size, as estimated by Cohen's $\delta$, is: $d=\frac{\hat x_1 - \hat x_2}{\hat s_{pooled}}$ Since the numerator is an estimate of difference in location, and the denominator is an ...
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230 views

How to use delta method for standard errors of marginal effects?

I am interested in better understanding the delta method for approximating the standard errors of the average marginal effects of a regression model that includes an interaction term. I've looked at ...
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11 views

Statistical comparison of 2 dependent cohen's ds

How would I statistically test the significane of the difference between two Cohen's d derived from different tests within the same sample? Specifically, in my neuroimaging data metabolism in brain ...
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1answer
47 views

Effectsize difference between Mann-Whitney U and t-Test

I have data that is officially not normally distributed (Kolmogorov-Smirnov test < .000 BUT N=around 1200 so K-S not really reliable). In plot I can see that form looks good but negatively skewed. ...
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2answers
104 views

Effect size for a one-sample t-test

Imagine I work in a screw factory (which is not true). We have been producing a series of 5cm-long (on average) screws for years. I want to modify the production parameters in order to save some money ...
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1answer
34 views

Effect sizes for post-hoc paired comparisons in one-way ANOVA

Is there any alternative (like Cohen's d in t-test) to report about effect sizes for post-hoc paired comparisons in a one-way ANOVA (3 factor levels, correlated samples)?. Many thanks!!
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1answer
86 views

Interaction terms and effect sizes in multiple regression

I know there are similar questions on here, but I can't quite find an answer that covers all of what I need. I am running multiple regression in r with two predictor variables and sometimes an ...
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1answer
315 views

Why is usually the acceptable probability of type 1 and type 2 errors different?

This question is raised by my supervisor and I don't know how to explain. Usually the accepted confident level is 0.95 which means that the probability of type 1 error is 5%. But the usually ...
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61 views

Effect sizes in within-subject design on R

I'm doing a meta-analysis but I need your precious help on couple things : 1) First, on R, in the compute.es package, I found only effect sizes computation formula ...
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1answer
48 views

When testing for a difference between effect sizes, is test power affected by their respective magnitude?

When comparing two effect sizes with a statistical test, does it matter for the test's power whether these effect sizes themselves are large or small? Imagine you are planning an experiment in which ...
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1answer
115 views

How to get proper effect size from LMM?

I now have a problem with effect size of LMM. Someone insisted that I should have effect sizes after p values. I then thought that I can use 'estimate' in the output of pairwise comparison using ...
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1answer
22 views

How are these negative values understood?

I can't find literature to understand this table. What I know doing my research is that an effect size should be between 0 and 1. when 0.2 is slow, 0,5 medium and 0.8 and higher , high. But In an ...
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32 views

Mann-Whitney U test [closed]

I am comparing 2 separate datasets with the Mann-Whitney U test. I am analyzing three separate parameters present in both datasets and want to know which parameter gives greatest separation between ...
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75 views

3 way mixed ANOVA & pairwise comparisons effect size

im in desperate need of some help for my data analysis assignment! I have a 3 way mixed anova- where I have 2 sig main effects, one significant two way interaction and the sig three way ...
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1answer
92 views

Calculating effect size (partial eta squared) for a planned comparison effect

I have a between-subjects ANCOVA (factors A and B, and covariate C), for which A*B is significant. I decomposed the interaction with a planned comparison described by the contrast A=(-1,1), B=(0,1), ...
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1answer
125 views

How to perform a meta-analysis of studies without a control group?

I want to meta-analyse some studies which I've already collected and review. However, the studies did not used control groups, due to the types of questions used. How can I do the meta-analysis or ...
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61 views

Is there an effect size for Kappa's?

I am staring a project on comparing standard ways of creating a classifier with some heuristic methods. The heuristic methods should result in a faster training for the classifier but should result in ...
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22 views

What is a “concordance score” for regression coefficients?

I came across this "concordance score" in a set of slides called Penalized regression methods for ranking variables by effect size, with applications to genetic mapping studies, by Ji Zhu: $$ ...
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3answers
59 views

Does the order of magnitude of sample values influence p-values and effect size?

When using an independent-samples t-test to compare two variables, do the absolute values of the samples affect the test statistic and the effect size? In other words, is it easier to obtain ...
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45 views

Statistically correct to compare two Spearman's $\rho$-Vaules?

I have different variables (A, B, C, D) which are all ordinal scaled. I have another variable (Z) which is ordinal scaled, too. My sample size is approx. 1.500. Is it in the statistical sense ...
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216 views

Calculating effect sizes and standard errors for the difference between two standardized mean differences

I have two related questions, both of which are related to a meta-analysis I am performing where where the primary outcomes are expressed in terms of the standardized mean difference. My studies have ...
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67 views

Calculating Hedge's g and its variance from t-statistic

I believe there is a way to calculate Hedge's g and its variance from a t-statistic. I have found the formulas to calculate Hedge's g from one-sample t, and from independent groups t. one sample: ...
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35 views

Obtaining Cohen's d from z-test statistic

After an ANOVA, I run post-hoc tests with the glht function in the multcomp package. glht ...
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3answers
110 views

Understanding $\chi^{2}$ and Cramér's $V$ results

I have two groups of buyers, A and B, and I want to test whether the difference between the percentage of them who would buy a ...
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49 views

Effect sizes from regression analysis and factor loadings

To do a meta analysis, I try to calculate effect sizes. In an article by Shah and Ward, the authors do a regression analysis after combining various factors by a CPA to four factors. The factor ...
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39 views

power analysis when mean and standard deviation are given

I have been asked to perform a sample adequacy test (i.e., I suppose, to verify what is the minimum difference that can be quantified between two grous) where a new sample (of which mu, sigma and ...
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25 views

simulate ANOVA data to follow a specific eta-squared

I am simulating RM-ANOVA data with three treatment conditions (one-way within subjects designs). I would like to be able to add an effect to the data so that eta-squared has a specific value. ...
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1answer
72 views

Question about EFFECT SIZE

I have a question. If I found the effects of a variable is insignificant (p>.05), but the effect size d is 0.2 (small effect). So I used GPower to calculate the power and I found it is 0.14, which ...
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2answers
53 views

What are real strengths of association when using Pearson correlation?

I have located a table that breaks downs Pearson's correlation values into 3 categories. See below: My question is this. One could have a large positive correlation of 1 as well as a perfect ...
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89 views

eta squared and partial eta squared: do they have the same effect size categorization (by cohen)?

I was computing partial eta squared for an ANOVA. I can only find a categorization for eta squared which are either 0.02 (small), 0.13 (medium), 0.26 (large) or .001 (small), .06 (medium) or .12 ...
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44 views

after using AIC, how to determine the contribution or effect size of a individual covariate?

I am confused and looking for advise. I have found myself in this same situation repeatedly in the last few months. I want to know if covariate X is influential or important. However, I also ...
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20 views

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 ...
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1answer
33 views

Using two one variable linear regressions on a single response variable to compare explanatory variables

I ran two single variable linear regressions $A$ and $B$. $A$ had a relatively large effect size $R^2$ = $.68$ while $B$ had $R^2$ = $.10$. Regressing the explanatory variable from $A$ (= $a$) on ...
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1answer
49 views

Designing Frequentist A/B Experiments

What parameters should one pre-specify before designing/running an experiment? (e.g. a two-sample, one-side, t-test) My understanding is that on establishes: Null hypothesis Maximum Significance ...
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Estimating Sample sizes for Null Hypothesis Testing

Wikipedia has the following table for computing sample sizes:                                       ...