(1) Used collect_data.R to extract connection graphs from all CRAN packages
    available as of 11/19/2009 by using read.dcf() to parse each package's
    DESCRIPTION file.

(2) Used count_analysis.R to find number of times each package was listed in
    a Depends, Suggests or Imports section. (The merging may have dropped some
    entries with 0 values in any of these columns.)

(3) Used graphviz.R to produce DOT files for dependency, suggestion and import
    graphs. These are too large to visualize, though.

(4) Used page_rank.R to calculate PageRank for depends, suggests and imports
    graphs.

(5) Used pool_analyses.R to plot relationships between various measures.