Posts Tagged ‘ ANOVA ’

Applied Statistics Lesson of the Day – Additive Models vs. Interaction Models in 2-Factor Experimental Designs

Applied Statistics Lesson of the Day – Additive Models vs. Interaction Models in 2-Factor Experimental Designs

In a recent “Machine Learning Lesson of the Day“, I discussed the difference between a supervised learning model in machine learning and a regression model in statistics.  In that lesson, I mentioned that a statistical regression model usually consists of a systematic component and a random component.  Today’s lesson strictly concerns the systematic component. An […]

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Example 2014.3: Allow different variances by group

February 27, 2014
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Example 2014.3: Allow different variances by group

One common violation of the assumptions needed for linear regression is heterscedasticity by group membership. Both SAS and R can easily accommodate this setting. Our data today comes from a real example of vitamin D supplementation of milk. Four sup...

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Applied Statistics Lesson of the Day – The Completely Randomized Design with 1 Factor

Applied Statistics Lesson of the Day – The Completely Randomized Design with 1 Factor

The simplest experimental design is the completely randomized design with 1 factor.  In this design, each experimental unit is randomly assigned to each factor level.  This design is most useful for a homogeneous population (one that does not have major differences between any sub-populations).  It is appealing because of its simplicity and flexibility – it can […]

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Some Common Approaches for Analyzing Likert Scales and Other Categorical Data

July 2, 2013
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Some Common Approaches for Analyzing Likert Scales and Other Categorical Data

Analyzing Likert scale responses really comes down to what you want to accomplish (e.g. Are you trying to provide a formal report with probabilities or are you trying to simply understand the data better). Sometimes a couple of graphs are sufficient and a formalize statistical test isn’t even necessary. However, with how easy it is […]

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Serious stats: using multilevel models to get accurate inferences for repeated measures ANOVA

June 13, 2013
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Serious stats: using multilevel models to get accurate inferences for repeated measures ANOVA

This article from my other blog may be of interest to readers of this blog: http://seriousstats.wordpress.com/2013/04/18/using-multilevel-models-to-get-accurate-inferences-for-repeated-measures-anova-designs/

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Neuroscience, statistical power and how to increase it

April 21, 2013
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Neuroscience, statistical power and how to increase it

There has been quite a bit of buzz recently about the Button et al. Nature Reviews Neuroscience paper on statistical power. Several similar reviews have been published in psychology and other disciplines and come to broadly the same conclusion - that m...

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Using multilevel models to get accurate inferences for repeated measures ANOVA designs

April 18, 2013
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Using multilevel models to get accurate inferences for repeated measures ANOVA designs

It is now increasingly common for experimental psychologists (among others) to use multilevel models (also known as linear mixed models) to analyze data that used to be shoe-horned into a repeated measures ANOVA design. Chapter 18 of Serious Stats introduces multilevel models by considering them as an extension of repeated measures ANOVA models that can […]

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Analyzing Pre-Post Data with Repeated Measures or ANCOVA

January 22, 2013
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Analyzing Pre-Post Data with Repeated Measures or ANCOVA

This kind of situation happens all the time, in which a colleague, a reviewer, or a statistical consultant insists that you need to do the analysis differently. Sometimes they're right, but sometimes, as was true here, the two analyses answer different research questions.

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Confusing Statistical Term #7: GLM

August 9, 2012
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Confusing Statistical Term #7: GLM

Like some of the other terms in our list--level and beta--GLM has two different meanings. It's a little different than the others, though, because it's an abbreviation for two different terms: General Linear Model and Generalized Linear Model. It's extra confusing because their names are so similar on top of having the same abbreviation.

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Serious stats book officially published

July 5, 2012
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Serious stats book officially published

My serious stats book is officially published (in the UK at least). The US release date is next month (August 7th). I'm not sure why the release is later (possibly extra shipping time for the books). The earlier European release date is I suppose compe...

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