Publications by Dan Mirman
New version of lme4
If you haven’t realized it yet, a new version of lme4 (version 1.0-4) was released recently (Sept. 21). For an end-user like me, there were not many changes, but there were a few:No more using the @ operator. After a very helpful email exchange with Ben Bolker, I came to realize that I shouldn’t have been using it in the first place, but I h...
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Three ways to get parameter-specific p-values from lmer
How to get parameter-specific p-values is one of the most commonly asked questions about multilevel regression. The key issue is that the degrees of freedom are not trivial to compute for multilevel regression. Various detailed discussions can be found on the R-wiki and R-help mailing list post by Doug Bates. I have experimented with three metho...
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Guidebook for growth curve analysis
I don’t usually like to use complex statistical methods, but every once in a while I encounter a method that is so useful that I can’t avoid using it. Around the time I started doing eye-tracking research (as a post-doc with Jim Magnuson), people were starting recognize the value of using longitudinal data analysis techniques to analyze fixat...
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Flip the script, or, the joys of coord_flip()
Has this ever happened to you?I hate it when the labels on the x-axis overlap, but this can be hard to avoid. I can stretch the figure out, but then the data become farther apart and the space where I want to put the figure (either in a talk or a paper) may not accommodate that. I’ve never liked turning the labels diagonally, so recently I’...
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Plotting mixed-effects model results with effects package
As separate by-subjects and by-items analyses have been replaced by mixed-effects models with crossed random effects of subjects and items, I’ve often found myself wondering about the best way to plot data. The simple-minded means and SE from trial-level data will be inaccurate because they won’t take the nesting into account. If I compute su...
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My "Top 5 R Functions"
In preparation for a R Workgroup meeting, I started thinking about what would be my “Top 5 R Functions”. I ruled out the functions for basic mechanics – save, load, mean, etc. – they’re obviously critical, but every programming language has them, so there’s nothing especially “R” about them. I also ruled out the fancy statistical ...
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How to learn R: A flow chart
I often find myself giving people suggestions about how to learn R, so I decided to put together a flow chart. This is geared toward typical psychology or cognitive science researchers planning to do basic data analysis in R. This is how to get started — it won’t make you an expert, but it should get you past your SPSS/Excel addiction. One da...
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Plotting Factor Analysis Results
A recent factor analysis project (as discussed previously here, here, and here) gave me an opportunity to experiment with some different ways of visualizing highly multidimensional data sets. Factor analysis results are often presented in tables of factor loadings, which are good when you want the numerical details, but bad when you want to conve...
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A little growth curve analysis Q&A
I had an email exchange with Jeff Malins, who asked several questions about growth curve analysis. I often get questions of this sort and Jeff agreed to let me post excerpts from our (email) conversation. The following has been lightly edited for clarity and to be more concise.Jeff asked:I’ve fit some curves for accuracy data using both linear ...
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