255 search results for "Anova"

Item Response Theory: Developing Your Intuition

September 10, 2012
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Item Response Theory: Developing Your Intuition

Suppose that you accepted my argument from the last two posts on halo effects and bifactor models.  As you might recall, I argued that when respondents complete rating scales, they predominating rely on their generalized impression with a more minor role played by the specific features that the ratings were written to measure.  Consequently, we...

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Data analysis using R – course in Essex

August 24, 2012
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Data analysis using R – course in Essex

This course is running 1-5 October at the University of Essex. There doesn’t seem to be a website but you register by writing to [email protected] Here’s what they say in their e-mail: Lecturers: Dr Werner Adler (University of Erlangen-Nuremberg; Co-author … Continue reading →

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INLA: Bayes goes to Norway

August 15, 2012
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INLA: Bayes goes to Norway

INLA is not the Norwegian answer to ABBA; that would probably be a-ha. INLA is the answer to ‘Why do I have enough time to cook a three-course meal while running MCMC analyses?”. Integrated Nested Laplace Approximations (INLA) is based … Continue reading →

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The Relative Importance of Predictors – Let the Games Begin!

August 9, 2012
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The Relative Importance of Predictors – Let the Games Begin!

What's the one thing we need to do?Marketing researchers are asked this question frequently whenever they analyze customer satisfaction data.  A company wishing to increase sales or limit churn wants to focus only on the most important determinants of those outcomes.   Given the limitations imposed by the available customer survey data, this strategic question is transformed quickly into a methodological one concerning how...

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Adventures at My First JSM (Joint Statistical Meetings) #JSM2012

August 6, 2012
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Adventures at My First JSM (Joint Statistical Meetings) #JSM2012

During the past few decades that I have been in graduate school (no, not literally) I have boycotted JSM on the notion that “I am not a statistician.” Ok, I am a renegade statistician, a statistician by training. JSM 2012 was held in San Diego, CA, one of the best places to spend a week during the summer. This...

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Example 9.36: Levene’s test for equal variances

June 25, 2012
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Example 9.36: Levene’s test for equal variances

The assumption of equal variances among the groups in analysis of variance is an expression of the assumption of homoscedasticity for linear models more generally. For ANOVA, this assumption can be tested via Levene's test. The test is a function of the residuals and means within each group, though various modifications are used, including the Brown-Forsythe...

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Split-plot 1: How does a linear mixed model look like?

June 24, 2012
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Split-plot 1: How does a linear mixed model look like?

I like statistics and I struggle with statistics. Often times I get frustrated when I don’t understand and I really struggled to make sense of Krushke’s Bayesian analysis of a split-plot, particularly because ‘it didn’t look like’ a split-plot to … Continue reading →

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The stimuli-as-fixed-effect fallacy

June 21, 2012
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Neuroskeptic has just blogged on a new paper by Judd, Westfall and Kenny on Treating stimuli as a random factor in social psychology: A new and comprehensive solution to a pervasive but largely ignored problem. I can't access the original pap...

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Experimental Design: Problem Set

June 21, 2012
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Experimental Design: Problem Set

QUESTIONSThe tensile strength of Portland cement is being studied. Four different mixing techniques can be used economically. The following data have been collected: MixingTechniques Tensile Strength (lb/in­­2) ...

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Color Palettes in RGB Space

June 20, 2012
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Color Palettes in RGB Space

Introduction I've recently been interested in how to communicate information using color. I don't know much about the field of Color Theory, but it's an interesting topic to me. The selection of color palettes, in particular, has been a topic I've been faced with lately. I downloaded 18 different sequential color palettes from Cynthia Brewer's

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