The simple linear regression model considers the relationship between two variables and in many cases more information will be available that can be used to extend the model. For example, there might be a categorical variable (sometimes known as a covariate) that can be used to divide the data set to fit a separate linear
AWStats is a free powerful and featureful tool that generates advanced web, streaming, ftp or mail server statistics, graphically. This log analyzer works as a CGI or from command line and shows you all possible information your log contains, in few graphical web pages. It uses a partial information file to be able to process large log files, often and quickly. It can analyze log files from all major server tools like Apache log files (NCSA combined/XLF/ELF log format or common/CLF log format), WebStar, IIS (W3C log format) and a lot of other web, proxy, wap, streaming servers, mail servers and some ftp servers.
CCOUNT is a free software package for market research / marketing research data cleaning, data weighting, manipulation, cross tabulation and data analysis. Similar to, and uses the same syntax and data format as SPSS-MR "Quantum"*, a well known commercial
cloc counts blank lines, comment lines, and physical lines of source code in many programming languages. It is written entirely in Perl with no dependencies outside the standard distribution of Perl v5.6 and higher (code from some external modules is embedded within cloc) and so is quite portable. cloc is known to run on many flavors of Linux, Mac OS X, AIX, Solaris, IRIX, z/OS, and Windows. (To run the Perl source version of cloc on Windows one needs ActiveState Perl 5.6.1 or higher, or Cygwin installed. Alternatively one can use the Windows binary of cloc generated with perl2exe to run on Windows computers that have neither Perl nor Cygwin.)