383 search results for "anova"

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

January 1, 2016
By

(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...

Ensuring R Generates the Same ANOVA F-values as SPSS

August 27, 2015
By

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....

Two-Way ANOVA with Repeated Measures

August 18, 2015
By

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

ANOVAs and Geomorph

April 1, 2015
By

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...

A function to help graphical model checks of lm and ANOVA

March 25, 2015
By

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

Generating ANOVA-like table from GLMM using parametric bootstrap

February 26, 2015
By

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

Performing ANOVA Test in R: Results and Interpretation

June 23, 2014
By

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...

ANOVA and Tukey’s test on R

June 13, 2013
By

OBS: This is a full translation of a portuguese version. In many different types of experiments, with one or more treatments, one of the most widely used statistical methods is analysis of variance or simply ANOVA . The simplest ANOVA can be called “one way” or “single-classification” and involves the analysis of data sampled from The post ANOVA...

June 13, 2013
By

Visualizing a One-Way ANOVA using D3.js

May 31, 2013
By

A while ago I was playing around with the JavaScript package D3.js, and I began with this visualization—that I never really finished—of how a one-way ANOVA is calculated. I wanted to make the visualization interactive, and I did integrate some interactive elements. For instance, if you hover over a data point it will show the residual, and its value will be highlighted in...