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

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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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9 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
31 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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22 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
36 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
30 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
43 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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14 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
49 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
84 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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36 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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7 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
40 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
50 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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29 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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36 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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24 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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7 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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13 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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26 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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18 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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48 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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20 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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42 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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71 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
42 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 ...
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1answer
49 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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7 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
11 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
25 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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28 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
23 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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32 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 ...
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1answer
20 views

Significance of a cluster with respect to the whole dataset

I mainly am a machine learning guy and my knowledge of statistics is a bit limited. I have a (small) dataset of objects described by two categorical variables: $$ \begin{array}{|l|l|l|l|l|} \hline ...
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1answer
106 views

Computing Paired Samples (pre/post) Effect Size with Limited Information

I'm conducting a meta-analysis using the Hedge's g effect size statistic. Many of the studies are only reporting: pre-treatment mean score pre-treatment standard deviation post-treatment mean score ...
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41 views

Interpretation of effect sizes

I made a conclusion after a lot of research on the internet and i want to know if it is sound in any way. Because i think i might have been thinking on this way too long. Here's the deal: we did an ...
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1answer
47 views
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23 views

Calculating effect size for model with incidence rate ratios?

I've got IRR from a GEE negative binomial with log link. I have within subjects effects (pre to post) and between subjects (difference in change between groups), how do I calculate effect sizes?
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28 views

Relation between variance stabilizing transformations and effect sizes?

When researching effect size for proportions, in particular the paper Effect-Size Indices for Dichotomized Outcomes in Meta-Analysis, that at least two of the usual effect sizes are realy variance ...
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54 views

R: Effect size from simple slopes

I have calculated simple slopes for a multiple regression using simpleSlope from package pequod(). Is there a way to easily compute an effect size for a single simple slope analysis from the output? ...
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11 views

effect sizes and significance

I had to do a two-way anova with as dependent variable a pretest to determine any pre-existing differences in the groups. It yielded one significant effect in with a low effect size η2= 0.046 and two ...
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1answer
96 views

How to show the Contribution of Independent variables in terms of percentage in Multiple regression?

I would like to show the independent variables (IV) contribution in percentage. For example, Regression equation is ...
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1answer
110 views

Calculating effect size (lnR) variances for studies with different study designs for use in meta-analysis

My question concerns the calculation of effect size variance for studies that are going to be included in a meta-analysis. I want to calculate variance so that I can weight each study by the inverse ...
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116 views

How can i calculate an effect size (cohen's d) from a linear random effects model (beta)

I am trying to figure out how to calculate a Cohen's d statistic for a linear random effects model. I did not do the analysis myself, I have read it in a journal article so i'm left to figure it out ...
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1answer
290 views
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1answer
139 views

Why is the p-value for Cohen's $d$ not equal to the p-value of a t-test?

I am using the package compute.es in R to calculate effect size from a $t$-test. The $t$-test is marginally significant with $p=0.05657$. When I run ...
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55 views

Two-way MANOVA - Total Effect of Independent Variables on Response Variables Together

I have run a two-way MANOVA in SPSS. In the model, there are two fixed (independent) variables A and B, and two response (dependent) variables X and Y. I am trying to ascertain the total effect of A ...
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1answer
43 views

Computing the true effect size from F-values and sample sizes?

I'm trying to extract a bunch of effect sizes from a couple of different studies in for which the authors have performed ANOVAs on their data. More specifically, I'm interested in the main effects of ...
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264 views

Interpreting partial eta squared and reporting it apa style

How do you interpret and report partial eta-squared in a two-way anova? I have run a two-way anova to inspect whether gender and level of education interact to have an effect on positive affect. ...
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29 views

Difference between measured factor, manipulated factor, covariates.

I am trying to understand this paragraph, and it would be great to have some extra clarity on what is meant? I'm trying to assess whether i can use this formula for collecting data for a ...