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

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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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15 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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18 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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4 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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10 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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19 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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15 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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45 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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14 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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16 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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32 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
33 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
31 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
8 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
20 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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13 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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1answer
12 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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21 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
19 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
84 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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0answers
37 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
40 views
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18 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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25 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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41 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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9 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
46 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 ...
2
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1answer
81 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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75 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
89 views
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1answer
102 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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37 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
35 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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192 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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22 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 ...
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4answers
4k views

A psychology journal banned p-values and confidence intervals; is it indeed wise to stop using them?

On 25 February 2015, the journal Basic and Applied Social Psychology issued an editorial banning $p$-values and confidence intervals from all future papers. Specifically, they say (formatting and ...
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3answers
414 views

Are smaller p-values more convincing?

I've been reading up on $p$-values, type 1 error rates, significance levels, power calculations, effect sizes and the Fisher vs Neyman-Pearson debate. This has left me feeling a bit overwhelmed. I ...
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0answers
19 views

Calculation of effect size for a mediation analysis with a dichotomous DV

I am using Haye's PROCESS macro to calculate the indirect effect (mediation) using a continuous IV, continuous mediator and a dichotomous DV. Haye's macro does not calculate an effect size for ...
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32 views

Best effect size estimator in simple linear regression?

Using a metric developed by someone else, I have calculated vegetation condition scores from a set of measured variables (about 1000 sites). I am using simple linear regression to determine how ...
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23 views

Determining the effect size using GPower

I have three ponds and would like to know how many random samples of algae I need to collect within each pond measuring 7 response variables. I would like to see how each pond responds to the 7 ...
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3answers
163 views

Why do irrelevant regressors become statistically significant in large samples?

I am trying to better understand statistical significance, effect sizes and the like. I have a perception (perhaps its wrong) that even irrelevant regressors often become statistically significant in ...
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56 views

Which method should I use to combine the data of my studies?

I want to make a meta-analysis on household consumption expenditures elasticity data. In these studies that I've got; methods and regions and etc. varies according to studies. But at last, the results ...
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1answer
130 views

Effect sizes (eta-squared) with confidence intervals for linear models

STATA has recently implemented effect size calculations for regression models in their postestimation procedures measures of effect size in Stata 13. It takes a regression or ANOVA object as input, ...
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79 views

R code for standardized coefficents and model effect size using nlme

I have fit a longitudinal random effects model using nlme and I prefer nlme because I can get p-values. While working with a ...
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2answers
100 views

Statistical significance versus sample size [duplicate]

Statistical significance of a (variable in a) model grows with sample size. Citing Gilbert (1986): If one uses test statistics with constant size (i.e. a constant degree of confidence), almost any ...
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624 views

Effect size to Wilcoxon signed rank test?

Some authors (e.g. Pallant, 2007, p. 225; see image below) suggest to calculate the effect size for a Wilcoxon signed rank test by dividing the test statistic by the square root of the number of ...
2
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1answer
52 views

Can you add up effect sizes of two related variables (e.g. age + age$^2$) from a single regression model?

I am interested in the effect of age on outcome Y. I have two nested linear regression models to test linear and quadratic effects of age: Y= $\beta_0$ + $\beta_1$ some_covariate + $\beta_2$ Age + ...
5
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1answer
75 views

What measure of effect size in ANOVA has mode at zero under the null (unlike $\eta^2$ that does not)?

I encountered a weird effect when computing eta squared in ANOVA. Here is a short simulation to demonstrate it. I simulate $k$ groups with $n=10$ each, with all values drawn from standard normal ...
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1answer
61 views

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 ...