Expand "Purpose of this Analysis"

[jashapiro]

Looking across the notebooks, the “Purpose of the analysis” section is usually a single sentence, and does not usually give any "why". For example, the for PCA for 02-microarray/dimension-reduction_microarray_01_pca.html, it reads:

This notebook illustrates one way that you can use microarray data from refine.bio to perform Principal Component Analysis (PCA) and plot the scores using ggplot2.

I think it would be helpful to expand many of these by a sentence or two. In this example, we might say something brief about what PCA is doing and how it is useful (maybe even how it is not).

[jaclyn-taroni]

Hard agree!