346 search results for "ANova"

A simple ANOVA

January 17, 2016
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A simple ANOVA

I was browsing Davies Design and Analysis of Industrial Experiments (second edition, 1967). Published by for ICI in times when industry did that kind of thing. It is quite an applied book. On page 107 there is an example where the variance of a process is estimated.DataData is from nine batches from which three samples were selected (A, B and...

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Error Control in Exploratory ANOVA’s: The How and the Why

January 1, 2016
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(This article was first published on The 20% Statistician, and kindly contributed to R-bloggers) In a 2X2X2 design, there are three main effects, three two-way interactions, and one three-way interaction to test. That’s 7 statistical tests.The probability of making at least one Type 1 error in a single ANOVA is 1-(0.95)^7=30%. There are earlier blog posts on this, but...

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Ensuring R Generates the Same ANOVA F-values as SPSS

August 27, 2015
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Ensuring R Generates the Same ANOVA F-values as SPSS

When switching to R from SPSS a common concern among psychology researchers is that R gives the "correct" ANOVA F-values. By "correct" they simply mean F-values that match those generated by SPSS. Because ANOVA F-values in R do not match those in SPSS by default it often appears that R is "doing something wrong". This is not the case....

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Two-Way ANOVA with Repeated Measures

August 18, 2015
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Two-Way ANOVA with Repeated Measures

NOTE: This post only contains information on repeated measures ANOVAs, and not how to conduct a comparable analysis using a linear mixed model. For that, be on the lookout for an upcoming post! When I was studying psychology as an undergraduate, one of my biggest frustrations with R was the lack of quality support for

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ANOVAs and Geomorph

April 1, 2015
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Within geomorph are several functions that perform analysis of variance (ANOVA), includingprocD.lm()procD.pgls()advanced.procD.lm()pairwiseD.test()pairwise.slope.test()trajectory,analysis()bilat.symmetry()plotAllometry() Inherent in all of these functions is a common philosophy for ANOVA (although other philosophies exist).  The geomorph ANOVA philosophy is that: (1) resampling (randomization) procedures are used to generate empirical sampling distributions to assess significance of effects, (2) effect sizes are estimated as standard deviates from such...

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A function to help graphical model checks of lm and ANOVA

March 25, 2015
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A function to help graphical model checks of lm and ANOVA

As always a more colourful version of this post is available on rpubs. Even if LM are very simple models at the basis of many more complex ones, LM still have some assumptions that if not met would render any interpretation from the models plainly wrong. In my field of research most people were taught

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A function to help graphical model checks of lm and ANOVA

March 25, 2015
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A function to help graphical model checks of lm and ANOVA

As always a more colourful version of this post is available on rpubs. Even if LM are very simple models at the basis of many more complex ones, LM still have some assumptions that if not met would render any interpretation from the models plainly wrong. In my field of research most people were taught

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Generating ANOVA-like table from GLMM using parametric bootstrap

February 26, 2015
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Generating ANOVA-like table from GLMM using parametric bootstrap

This article may also be found on RPubs: http://rpubs.com/hughes/63269 In the list of worst to best way to test for effect in GLMM the list on http://glmm.wikidot.com/faq state that parametric bootstrapping is among the best options. PBmodcomp in the pbkrtest package implement such parametric bootstrapping by comparing a full model to a null one. The

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Generating ANOVA-like table from GLMM using parametric bootstrap

February 26, 2015
By
Generating ANOVA-like table from GLMM using parametric bootstrap

This article may also be found on RPubs: http://rpubs.com/hughes/63269 In the list of worst to best way to test for effect in GLMM the list on http://glmm.wikidot.com/faq state that parametric bootstrapping is

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Performing ANOVA Test in R: Results and Interpretation

June 23, 2014
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Performing ANOVA Test in R: Results and Interpretation

When testing an hypothesis with a categorical explanatory variable and a quantitative response variable, the tool normally used in statistics is Analysis of Variances, also called ANOVA.In this post I am performing an ANOVA test using the R programming language, to a...

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