Publications by John Quick
R Tutorial Series: One-Way ANOVA with Pairwise Comparisons
When we have more than two groups in a one-way ANOVA, we typically want to statistically assess the differences between each group. Whereas a one-way omnibus ANOVA assesses whether a significant difference exists at all amongst the groups, pairwise comparisons can be used to determine which group differences are statistically signific...
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Statistical Analysis with R Book Reviews
Reviews of my Statistical Analysis with R book have started to emerge online and I am writing today to share them with potential readers and recommenders. Reviews The following is a list of online reviews for Statistical Analysis with R. If you have written a review of the book and would like it to be featured in this post, please co...
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R Tutorial Series: Two-Way ANOVA with Interactions and Simple Main Effects
When an interaction is present in a two-way ANOVA, we typically choose to ignore the main effects and elect to investigate the simple main effects when making pairwise comparisons. This tutorial will demonstrate how to conduct pairwise comparisons when an interaction is present in a two-way ANOVA. Tutorial FilesBefore we begin, you ma...
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R Tutorial Series: One-Way Repeated Measures ANOVA
Repeated measures data require a different analysis procedure than our typical one-way ANOVA and subsequently follow a different R process. This tutorial will demonstrate how to conduct one-way repeated measures ANOVA in R using the Anova(mod, idata, idesign) function from the car package. Tutorial FilesBefore we begin, you may want t...
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Book Review: R Graphs Cookbook
Book InformationMittal, H. (2011). R graphs cookbook. Birmingham, UK: Packt Publishing Ltd.AudienceThe book’s stated audience is anyone who is familiar with the basics of R, as well as expert users who are looking for a graphical reference. However, it is my opinion that the book is better suited for advanced users who are already somewhat fami...
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R Tutorial Series: Two-Way Repeated Measures ANOVA
Repeated measures data require a different analysis procedure than our typical two-way ANOVA and subsequently follow a different R process. This tutorial will demonstrate how to conduct two-way repeated measures ANOVA in R using the Anova() function from the car package. Note that the two-way repeated measures ANOVA process can be ver...
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R Tutorial Series: Two-Way ANOVA with Unequal Sample Sizes
When the sample sizes within the levels of our independent variables are not equal, we have to handle our ANOVA differently than in the typical two-way case. This tutorial will demonstrate how to conduct a two-way ANOVA in R when the sample sizes within each level of the independent variables are not the same. Tutorial FilesBefore we ...
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R Tutorial Series: ANOVA Pairwise Comparison Methods
When we have a statistically significant effect in ANOVA and an independent variable of more than two levels, we typically want to make follow-up comparisons. There are numerous methods for making pairwise comparisons and this tutorial will demonstrate how to execute several different techniques in R. Tutorial FilesBefore we begin, yo...
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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 datasets for our omnibus ANOVA and follow-up comparisons. This tutorial will demonstra...
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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 January 17, we have had about 150 visits per day and over 19,000 total page views. ...
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