Category Archives: Data analysis

Pearson’s r: Not a good measure of electoral persistence

Pearson’s product-moment correlation, \(r\), is an incredibly useful tool for getting some idea about how two variables are (linearly) related. But there are times when using Pearson’s \(r\) is not appropriate and, even if linearity and all other assumptions hold, … Continue reading

Posted in Data analysis, Graphics, Poland, Political parties, R | 2 Comments

Welford’s method for calculating the sample variance: An implementation in Scheme

John Cook has three entries up on his blog discussing the pitfalls of calculating the sample variance using the mathematical textbook definitions. He provides a Monte Carlo comparison of methods here, and a theoretical discussion here. He also provides a … Continue reading

Posted in Code, Data analysis, Scheme | Leave a comment

Principal component analysis: some introductory resources

Principal component analysis (along with exploratory and confirmatory factor analysis) isn’t something we were exposed to in our Political Science methods sequence here at OSU. However, because they seem to come up from time to time, it’s probably a good … Continue reading

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A simple frequency plot

I’m currently working on a paper that uses Polish survey data (EVS 2008). I am specifically looking at regional variation in particular responses. Because there are only around 1800 observations in the survey, which are split across 66 subregions of … Continue reading

Posted in Data analysis, Graphics, R | 1 Comment