FPL Statistics Group

FORTRAN code for a confidence interval on the ratio of the coefficients of variation of two normally distributed populations


If you would simply like to run this code over the Web, go here.

The theory behind this program is discussed in two publications:


The FORTRAN source for this code comes in five files:

  1. covratio.f --- A FORTRAN main routine written by Steve Verrill of the USDA Forest Service Forest Products Laboratory.
  2. rnor.f --- rnor is a FORTRAN routine that generates normally distributed random numbers with mean 0, variance 1. It was written by David Kahaner and George Marsaglia. It includes uni, a FORTRAN routine that generates uniform random numbers on [0,1]. uni was written by James Blue, David Kahaner, and George Marsaglia.
  3. dfzero.f --- dfzero is a FORTRAN routine that searches "for a zero of a function F(X) in a given interval (B,C)". It was written by L.F. Shampine and H.A. Watts.
  4. dpsort.f --- dpsort is a FORTRAN routine that sorts double precision numbers. It was written by Steve Verrill.

The program also depends upon DCDFLIB. DCDFLIB is a public domain library of "routines for cumulative distribution functions, their inverses, and their parameters." It was produced by Barry Brown, James Lovato, and Kathy Russell of the Department of Biomathematics, M.D. Anderson Cancer Center, The University of Texas. DCDFLIB can be found at http://biostatistics.mdanderson.org/SoftwareDownload/SingleSoftware.aspx?Software_id=21 .


If you have questions about this software, or suggestions for improvement, please contact Steve Verrill at sverrill@fs.fed.us or 608-231-9375.
[Forest Service] [Forest Products Lab] [FPL Statistics Group]

Last modified on 9/9/09.

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