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

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Testing if two variables have significantly different effects on the data

I'm looking for a way to test if two variables have significantly different effects on my data. I'm also interested in a way to test if they have the same effect. Currently, I'm jointly calculating ...
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10 views

How to calculate the effect size after Welch ANOVA?

I used oneway.test() because Levene's test indicated heterogenity of variance. Unfortunately, I don't know how to calculate the effect size now. Does anybody have ...
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14 views

Bootstrapping effect size measures in a repeated measures design

A journal that people in my lab are submitting to asks for confidence intervals for effect size measures. We have a $(3) \times (3)$ design where each subject completes 3 blocks of trials, containing ...
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7 views

Determining partial eta squared from an anova table without SS error

I was given the following information and asked to calculate partial eta squared: ...
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28 views

How to calculate the sample size for proportions using Effect Size?

I need to determine the sample size for my experiment. In my experiment I will select a set of x projects, from a population of N project. For the sample x projects will apply a treatment to know the ...
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24 views

How do I convert $\eta^2$ to Pearson's r?

I am doing a meta-analysis of associations between sets of variables that are essentially all continuous. However, many studies operationalised them at 'lower' levels, and I have (converted to) most ...
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21 views

Is covariance a measure of effect size?

Is covariance a measure of effect size? Since correlation is such a measure, and correlation is normalized covariance, I would think so, but I'd like to know for sure.
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1answer
43 views

Perfect separation of two groups but rs is not 1

I have a dichotomous variable (group 1 and 2) and an ordinal scaled variable. The values of the ordinal scaled variable for group 1 are always lower than those for group 2: As I understand it, this ...
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18 views

Calculating effect sizes for mixed effect logistic regression to determine subsequent sample size

We conducted a previous preliminary study using 40 participants. We analyzed the data using the lme4 package in R to conduct a mixed effect logistic regression. We ...
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3answers
62 views

Cohens d effect sizes

I'm using Cohens d effect sizes as a means of providing a magnitude based inference in a study I'm conducting. I just wanted to clarify if I'm correct here: Anything between .0 and .2 is small. ...
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1answer
30 views

Q-Test of Heterogeneity for only two effect sizes?

I am using the Q-Test of Heterogeneity to investigate if several effect sizes derived from two different studies are significantly different from each other. More precisely, I have, for every effect ...
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34 views

Effect size for contrasts in hierarchical Bayesian “ANOVA”

Kruschke (2014) shows in his book how to compute posterior distributions of effect sizes (standardized mean difference) for the Bayesian analogues of frequentist independent-samples t-tests, and ...
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24 views

Combining effect sizes in binary data

I'm working on combining effect sizes for a meta-analysis when one study reports multiple effects for the same construct. To accomplish this, I'm using the equation provided in the Borenstein ...
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37 views

For Mann-Whitney, should I report effect size or Hodges-Lehmann pseudomedian?

When reporting a Mann-Whitney-U test result, is it better to report it's effect size or the Hodges-Lehmann pseudomedian (as R give us as "difference in location") ?
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18 views

Two years of data with pre/post, need to figure out size of impact

I have 2 data sets: 2013-14 and 2014-15. Each year has pre and post data, measuring literacy. Sample size is 101 in one year and 93 in the other. I would like to determine if 2014-15 results were ...
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38 views

How to compare explained variances of nested multivariate multiple regression models?

I have two groups of continuous* variables - let's call them MF (5 variables) and OR (2 variables), plus some demographics. It has been previously found that the MF are associated with one of the OR ...
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1answer
28 views

Why do I get completely different Effect Sizes using same data but different methods?

When I calculate Effect Sizes (Cohen's d) on the same study using different methods I get completely different effect sizes. For example: (t=4.81, P<0.001, d=0.41) I also calculated d=0.41 using ...
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29 views

Okay to use oneway ANOVA to compare these 3 group proportions from aggregated dataset?

My situation: I am assessing outcomes of a university course redesign. One of the goals of the redesign project was to increase successful course completion, as measured by a decrease in the course ...
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12 views

How to calculate effect size confidence interval with multiple replications at multiple sites?

Let’s say we have an experiment at one location evaluating the effect of some sort of treatment on a control condition (n=4). We calculate the effect size as (Treated – Control)/Control*100. So for ...
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1answer
54 views

How to calculate the effect size of differences in groups using dummies in multiple regression?

I am running a multiple regression analyses on a sample of 1800 respondents. The dependent variable is the mean of a 5-point likert scale and I have 6 predictors (antecedents) also using mean of ...
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29 views

Effect size for goodness of fit chi-square

I would like to assess the effect size of a goodness of fit chi-square test. I have a variable that can have 3 states and test against a custom expected value. I used a variation Cramér's V for a ...
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2answers
45 views

Categorical Predictors and categorical responses

I have a dataset consisting of 5 categorical predictors and a categorical response (class). I want to find out which predictor has an effect on the response. Additionally, I can't guarantee whether ...
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1answer
49 views

How do I calculate the effect size for a Spearman's correlation? Is it the same as for Pearson's correlation?

I'm having trouble understanding how can I calculate the effect size for a Spearman's correlation. I have the following results: rho= .352, df= 83, p<.01. Thanks!
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1answer
53 views

What is Pearson's r association strength?

I am trying to grasp the concept of magnitude-of-effect estimations, as opposed to standard null hypothesis testing procedures. According to a paper by (Snyder & Lawson, 1993) the ...
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31 views

Eta square and effect size in General Linear Model

I have an unbalanced data set that is categorized in 3 different topics. I wanted to see that how these different topics are effecting the data. So I used ...
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1answer
56 views

Is there any rule of thumb to classify $R^2$ as small, medium or large effect size?

I have seen authors saying $R^2 = .13$ is moderate, but they don't mention any source.
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2answers
137 views

Comparing the Fold Change (Effect size) after a treatment

I have been using this site for the past year to get tips on stats but I have run into a problem that I cannot overcome. It isn't too complicated, but I am not sure how to determine significance or if ...
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43 views

Calculating the covariance of effect sizes for multiple-treatment multiple-enpoint studies

I'm interested in finding the covariance of effect sizes for multiple-treatment multiple-outcome design given the scenario below. Gleser and Olkin (2009) provided the formula for the estimating the ...
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8 views

how to report effect sizes for average MAPE when comparing methods

My question is around how to report effect sizes ? I have 2 different methods and a naive method: I have method 1 applied to 1000 time series data and its average symmertric Mean Abs Percentage ...
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1answer
46 views

Compare two t-statistics

In a nutshell: I have performed two t-tests (A und B, each two-samples/paired). Both found significant differences. Can I tell, whether the difference observed in comparison A is significantly larger ...
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1answer
64 views

Modelling combined linear and quadratic age effects

I am running a GLM (Type III) with several predictors, including ${\rm age}$ and ${\rm age}^2$ as predictors. I am interested in knowing the combined effect size and p-value of ${\rm age}+{\rm ...
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39 views

Can I use a partial eta squared on t-test results?

I am currently trying to decide which effect size is the most appropriate for my results. I have conducted a repeated measures ANOVA, there are five variables in the ANOVA, all of which are within ...
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64 views

How do I calculate the effect-size of an unequal sample size independent t test?

Given the following parameters, how do I calculate the effect size of an independent unequal sample size t test? ...
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35 views

How do I calculate the variance of a mean difference effect size that has been converted to Fisher's z for meta-analysis?

To be able to compare different types of effect sizes, I am converting my effect sizes that are originally mean differences into correlation coefficients. I am using the following formula: d <- (t ...
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10 views

Calculating eta squared in 2 or 3 way ANOVAs

Does anyone know how you calculate eta squared (not partial eta squared) for 2 and 3 way repeated measures ANOVAs?
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19 views

Normality considerations for 'Effect Size'

What are the normality considerations while calculating Effect Size (http://en.wikipedia.org/wiki/Effect_size). Can different methods for calculating effect size be classified into parametric and ...
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1answer
51 views

Calculating effect sizes without SDs or sample sizes for meta-analysis

I'm coding articles for a meta-analysis looking at group differences on dichotomous and continuous outcomes. Groups are not the same size. Continuous outcome ES is standardized mean difference and ...
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24 views

Effect size for two-sample test with complications such as multiple data per subject

I have a simple hypothesis, that my dependent variable depends on a two-level factor Condition. Ideally I would like get a measure of Cohen's D, with confidence interval. The problem is my model is ...
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49 views

Will this invalidate my meta-analysis

I am pooling scores for my meta-analysis. The outcome measure is the proportion of children that pass a task. The data reported is given in three ways: 1) When children are tested with the task ...
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24 views

Calculating Cohen's d when df is Sattethwaite adjusted

Is it inappropriate to convert a t-statistic to Cohen's d if the independent groups have missing data estimated (MLE), and the df is much larger than it would be if you just entered the sample sizes? ...
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82 views

How do I calculate Omega-squared for the Multivariate effect in MANOVA?

I did a one-way MANOVA using SPSS and reported the partial eta-squared for the overall multivariate effect as well as for the follow-up ANOVAs (provided on the SPSS output). The editor wants me to use ...
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114 views

What is the difference between Average Partial Effects (APE) and Average Marginal Effects (AME)?

In this answer, the terms Average Partial Effects (APE) and Average Marginal Effects (AME) are used interchangeably. But in this paper, the terms are used to mean different things (page 75). But it's ...
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1answer
58 views

How do I statistically test whether two intervention types have significantly different effects in a meta-analysis?

I have the following problem: I am researching the difference in effects (as measured by standarized mean differences (SMD)) of two intervention types. (let's call them intervention 1 and intervention ...
2
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1answer
64 views

Describing trend magnitude or detecting trends

I have time series data. One observation per time period, about 10 observations or so. When describing the data (I am interested in descriptive statistics), I'd like to say that there is either a ...
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12 views

Disadvantages of common language effect size (CLES)

I recently read about common language effect size (CLES : https://en.wikipedia.org/wiki/Effect_size#Common_language_effect_size). It immediately appealed to me as an easily understandable number. I ...
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1answer
14 views

How to get common language effect size (CLES) with paired groups

Common language effect size (CLES : https://en.wikipedia.org/wiki/Effect_size#Common_language_effect_size) is calculated as proportion of all possible pairs of 2 group values which are more for one ...
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1answer
27 views

Common language effect size- place of equality

In Common language effect size (CLES) (http://en.wikipedia.org/wiki/Effect_size#Common_language_effect_size) how are cases with equality managed. Suppose there are 10 cases in each of control and ...
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46 views

Comparing effect sizes of two treatments from a large number of studies

I suppose this would be some kind of meta-analysis. I would like to compare the effect sizes of two treatments from a large number of published studies. I would like to show that the other treatment ...
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2answers
33 views

How do I calculate effect size for percentages of totals?

I apologize if this questions is poorly worded or has a very simple answer but I work in a field very different than statistics. I am looking at diction (word use) in books from two different artistic ...
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40 views

Where does this formula for calculating pooled standard deviation for calculating Cohen's d come from?

On this page, it is said that the pooled standard deviation for calculating Cohen's $d$ can be calculated as $\displaystyle SD_{pooled} = \sqrt{\frac{SD_{1}^{2}+SD_{2}^{2}}{2}}$. Where does this ...