FPL Statistics Group





Power Curve, ASTM, 9/00

This program is designed to let members of ASTM study a proposed acceptance test of duration of load samples. As of 9/1/00, it is in draft form. It is likely that it will never be very polished.

Here is the code for the Perl program that handles the data generated by this form. Here is the code for the FORTRAN program that actually performs the simulation. Here is a letter [LaTeX version][postscript version] that describes the program. If you detect any errors in this material, please contact Steve Verrill at sverrill@fs.fed.us or 608-231-9375.

How many "90 day strength reductions" do you want to consider?

What are they in percent?
(A 90 day strength reduction of 45 percent means that the median time to failure for a specimen loaded at 55 percent of its original strength is 90 days.)

How many coefficients of variation (cv) do you want to consider?
(The coefficent of variation of a property is 100 x (standard deviation)/mean.)

What are they?
(for example, 20 for a 20% coefficient of variation)

How many items will be tested in the unaged batch?
(e.g., 28)(1 to 200)

What order statistic from the unaged batch are you using to set the load level?
(e.g., 1)

What fraction of the load level will be applied to the specimens in the second and (possibly) third batches?
(e.g., .55)

How many failures are permitted in the second batch?
(e.g., 0)

If the material barely fails the first test (by 1 too many failures), how many items will be tested in the third batch?
(e.g., 25)(0 to 200)

How many failures are permitted in the third batch?
(e.g., 0)

What is the correlation in strength between the matched specimens?
(e.g., 0.70)

How many trials do you want in the simulation?
(between 1 and 10000)

What is the starting value for the random number generator?
(between 1 and 10000000)

What name do you want for your results file?

The name should be unique to you to prevent the file from being accidentally overwritten by another user.

Since you will see an html document that presents the results as soon as you execute the program, you may not want an ascii copy. However, we do provide this option.

The ascii file will be written in the pub/data anonymous ftp directory. If a file by the same name already exists in the directory, the new results will be appended to the existing file. Check the anonymous ftp link for directions about retrieving the file.

If ftp does not run on your machine, e-mail me at sverrill@fs.fed.us and ask me to e-mail the results file to you. Do this quickly as the pub/data directory is cleaned weekly.





For further information, please contact Steve Verrill at sverrill@fs.fed.us or 608-231-9375.
[Forest Service] [Forest Products Lab] [FPL Statistics Group]


Last modified on 9/7/00.




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