Quantreg -- Quantile Regression (Version 2.0) This is a submission to compute regression quantiles and some related rank statistics. It is a revision of a prior submission to incorporate some recent develoopments in rank based inference which employ regression quantile ideas. The submission consists of: rq.r--A ratfor subroutine and several S functions: rq--which directly calls rq.o trq--which computes analogues of the trimmed mean for regression trq.print--which prints ls.print style output for trq qrq--which is called by trq ranks--which computes a vector of rank statistics from rq() output rrs.test--which computes tests of linear hypotheses rq.omega--estimates a scale parameter for the covariance matrix dn--computes bandwidth for sparsity estimate These eight functions all reside in a file called rq.s which could be read by S with the source() command. Help files for the S functions are also provided in the directory doc and could be moved to the appropriate .Data/.Help directory. The files were packaged as a unix shar archive. A Makefile generated by the S CHAPTER command has been included to automate this process. It has been tested on Sun hardware, but may need editing. With luck you might try make install make load make clean If this works smoothly then invoking Splus in this directory will automatically load the new rq function and you can proceed from there. This software has been submitted to Statlib and may be freely used and redistributed for non-commercial purposes. No guarantees are offered or implied. Comments, bug reports, etc are welcome and should be sent to roger@ysidro.econ.uiuc.edu or to Roger Koenker Department of Economics University of Illinois Champaign, Illinois, 61820 Acknowledgements: Thanks to all those who have contributed comments on this software following its initial submission in 1991, particularly to Gib Bassett, Steve Portnoy, Jana Jureckova, and Cornelius Gutenbrunner. Special thanks to Pin Ng (U. of Houston) for help in preparing the new version.