277 search results for "ANova"

ggplot2 joy

February 25, 2011
By
ggplot2 joy

I’ve been working on a long-term (25+yr) longitudinal study of rheumatoid arthritis with my boss. He just walked in and asked if I could create a plot showing the trajectory of pain scores over time for each subject, separated by educational level (4 groups). Having now worked with ggplot2 for a while, and learning more

Read more »

Statistical Analysis with R, a Review

February 12, 2011
By
Statistical Analysis with R, a Review

Long Version: I have a Bachelor’s degree in Computer Science.  I’m pretty handy when it comes to

Read more »

New edition of “R Companion to Applied Regression” – by John Fox and Sandy Weisberg

December 10, 2010
By
New edition of “R Companion to Applied Regression” – by John Fox and Sandy Weisberg

Just two hours ago, Professor John Fox has announced on the R-help mailing list of a new (second) edition to his book “An R and S Plus Companion to Applied Regression”, now title . “An R Companion to Applied Regression, Second Edition”. John Fox is (very) well known in the R community for many contributions to R, including the...

Read more »

All together now – Confirmatory Factor Analysis in R

December 8, 2010
By

Describing multivariate data is not easy. Especially, if you think that statisticians have not developed any new tools after the ANOVA and principal component analysis (PCA). For social and experimental scientists the most important new technique are structural equation models that combine measurement models (that substitute reliability analysis and PCA) and structural models (that substitute

Read more »

Another boring blog

December 2, 2010
By
Another boring blog

I recently decided to create two blogs as outlets for my research.  The first (The Richness of Life) focuses more on the organisms I work with as an ecologist and my general interest as a student of natural history.  This blog on Quantitative...

Read more »

A small and lonely sea urchin…

August 22, 2010
By
A small and lonely sea urchin…

A few weeks ago, a paper on which I am a co-author was accepted for publication in the french ecological journal Life & Environment. In this paper, we evaluate the consequences of recreative harvesting on three populations of sea urchins (…)Read the rest of this entry »

Read more »

Using Optmatch and RItools for Observational Studies

July 29, 2010
By
Using Optmatch and RItools for Observational Studies

I am a contributor to the optmatch and the RItools packages for R. These two packages are separate, but complimentary. Both packages provide tools for adjusting observational data to exhibit “balance” on observed covariates. In a randomized control trial, treatment and control groups should have identical distributions over all covariates, observed and unobserved. Matching provides a...

Read more »

R Commander – two-way analysis of variance

June 25, 2010
By
R Commander – two-way analysis of variance

Two way analysis of variance models can be fitted to data using the R Commander GUI. The general approach is similar to fitting the other types of model in R Commander described in previous posts. Fast Tube by Casper The “Statistics” menu provides access to some analysis of variance models via the “Means” sub-menu: Multi-way ANOVA – the

Read more »

R Commander – one-way analysis of variance

June 25, 2010
By
R Commander – one-way analysis of variance

One way analysis of variance models can be fitted to data using the R Commander GUI. The general approach is similar to fitting the other types of model in R Commander described in previous posts. Fast Tube by Casper The “Statistics” menu provides access to some analysis of variance models via the “Means” sub-menu: One-way ANOVA – the

Read more »

Do Not Log-Transform Count Data, Bitches!

June 17, 2010
By
Do Not Log-Transform Count Data, Bitches!

OK, so, the title of this article is actually Do not log-transform count data, but, as @ascidacea mentioned, you just can’t resist adding the “bitches” to the end. Onwards. If you’re like me, when you learned experimental stats, you were taught to worship at the throne of the Normal Distribution. Always check your data and

Read more »