X es la matriz centrada (X is the centered matrix). Xcov es la matriz de covarianzas de X (Xcov is the covariance matrix of X).Con la función "eigen" calculamos los "eigenvectors" y "eigenvalues" de Xcov.(With the function "eigen" we calculate the "ei...
Seeing as I’m on a bit of an XPath kick as of late, I figured I’d continue on scraping search results but this time from Yahoo.com Rolling my own version of xpathSApply to handle NULL elements seems to have done the trick and so far it’s been relatively easy to do the scraping. I’ve created 
In general, the standard practice for correcting for population stratification in genetic studies is to use principal components analysis (PCA) to categorize samples along different ethnic axes. Price et al. published on this in 20...
My previous post talked about how we can employ PCA on the data for multiple stock returns to reduce the number of variables in explaining the variance of the underlying data. But the idea was greeted with skepticism by many. A caveat to the applicatio...
For my first contribution to the blog, I wanted to make some kind of enlightening visualization of campaign finance disclosure data from the Federal Election Commission’s website. It looks like they’re working on some new, easy-to-use data dumps here, but … Continue reading →
While working for my Financial economics project I came across this elegant tool called Principal component analysis (PCA)which is an extremely powerful tool when it comes to reducing the dimentionality of a data set comprising of highly correlated var...
I normally work with full numerical data, not categorical data. R, when using read.csv() seems to recognize such categories and marks the column as to have factor levels. This is useful indeed. However, I wanted to make a PCA biplot on this data, so wa...
Over the past couple of days I played around with the data sets of the World Bank, and I have to admit that I am blown away by it. It is amazing, to see what is available on their web site. It is worth visiting their Data Visualisation Tools page. It i...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
