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...
184 search results for "ANOVA"
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 →
Confidence intervals with tiers: functions for between-subjects (independent measures) ANOVA
In a previous post I showed how to plot difference-adjusted CIs for between-subjects (independent measures) ANOVA designs (see here). The rationale behind this kind of graphical display is introduced in Chapter 3 of Serious stats (and summarized in my earlier blog post). In a between-subjects – or in indeed in a within-subjects (repeated measures) – design 
The stimuli-as-fixed-effect fallacy
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...
Experimental Design: Problem Set
QUESTIONS
- The tensile strength of Portland cement is being studied. Four different mixing techniques can be used economically. The following data have been collected:
Mixing Techniques | Tensile Strength (lb/in2) | |||
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
