383 search results for "anova"

Functional ANOVA using INLA – update

February 29, 2012
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Functional ANOVA using INLA – update

INLA author Håvard Rue wrote me to point out a problem in the Functional ANOVA code given in this post. I made a mistake in setting the precision of the fixed effects (I used “default” instead of “prec”). I’ve put Håvard’s corrected version of the code below.  

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Power and Sample Size for Repeated Measures ANOVA with R

January 20, 2012
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Power and Sample Size for Repeated Measures ANOVA with R

Background One of my colleagues is an academic physical therapist (PT), and he's working on a paper to his colleagues related to power, sample size, and navigating the thicket of trouble that surrounds those two things. We recently got together to walk through some of the issues, and I thought I would share some of the wildlife we observed...

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Functional ANOVA using INLA

January 13, 2012
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Functional ANOVA using INLA

Ramsay and Silverman’s Functional Data Analysis is a tremendously useful book that deserves to be more widely known. It’s full of ideas of neat things one can do when part of a dataset can be viewed as a set of

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Calculating and graphing within-subject confidence intervals for ANOVA

October 4, 2011
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Calculating and graphing within-subject confidence intervals for ANOVA

Psychologists are gradually coming round to the view that it is a good idea to present interval estimates alongside point estimates of statistics. The most common statistic reported in psychology research is almost certainly the mean (strictly...

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Two-Way PERMANOVA (with Vegan-Function adonis) Using Customized Contrasts

August 8, 2011
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Two-Way PERMANOVA  (with Vegan-Function adonis) Using Customized Contrasts

...say you have a multivariate dataset and a two-way factorial design - you do a PERMANOVA and the aov-table (adonis is using ANOVA or "sum"-contrasts) tells you there is an interaction - how to proceed when you want to go deeper into the ana...

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Legendre & Borcard: Nested ANOVA by Permutation

May 30, 2011
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Legendre & Borcard: Nested ANOVA by Permutation

..here's a very illustrative R-Script example by Legendre & Borcard showing how a Nested ANOVA can be done by permutation.Read more »

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One-way ANOVAs in R – including post-hocs/t-tests and graphs

May 11, 2011
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One-way ANOVAs in R – including post-hocs/t-tests and graphs

In this post, I go over the basics of running an ANOVA using R. The dataset I’ll be examining comes from this website, and I’ve discussed it previously (starting here and then here). I’ve not seen many examples where someone runs through the … Continue reading →

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Adonis (PERMANOVA) – Assumptions

April 26, 2011
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Adonis (PERMANOVA) – Assumptions

Before you use PERMANOVA (R-vegan function adonis) you should read the user notes for the original program by the author (Marti J. Anderson) who first came up with this method. An important assumtption for PERMANOVA is same "multivariate spread&qu...

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R Tutorial Series: 2011 ANOVA Article Data

March 28, 2011
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R Tutorial Series: 2011 ANOVA Article Data

Having wrapped up a recent flurry of R ANOVA articles (and exhausted my knowledge of the subject), I decided to take a look at the R Tutorial Series' Google Analytics data from the past few months. Since I posted the Two-Way Omnibus ANOVA article on J...

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R Tutorial Series: Applying the Reshape Package to Organize ANOVA Data

March 14, 2011
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R Tutorial Series: Applying the Reshape Package to Organize ANOVA Data

As demonstrated in the preceding ANOVA tutorials, data organization is central to conducting ANOVA in R. In standard ANOVA, we used the tapply() function to generate a table for a single summary function. In repeated measures ANOVA, we used separate da...

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