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From Philippe Mouawad <philippe.moua...@gmail.com>
Subject Re: [GitHub] jmeter issue #296: Bug 61078 - Percentile calculation error
Date Sat, 03 Jun 2017 08:55:52 GMT
On Wed, May 31, 2017 at 2:54 PM, Vladimir Sitnikov <
sitnikov.vladimir@gmail.com> wrote:

> Philippe>- switch everywhere to R1 (also in commons-math)
>
> Can you please clarify why do you prefer R1?
>

Because from what the reporter wrote, it looked good to me:
"If the 90% percentile is 1200 ms than that means that 90% of tests take no
more than 1200 ms"

And there is a another pragmatic point, it seems JOrphan implementation is
R1 once we fix the issue.



> I'm inclined to R8 (as it is recommended by R for sample quantile
> calculation).
>
> 1) I think interpolation would reduce run-to-run variance.
> 2) Interpolation-like estimation is easier to implement. For instance, if
> HdrHistogram estimator is added, then its result would be closer to R8
> rather than to R1.
>

ok


>
> I don't think "the result of 90% is one of the sample response times" is
> important. The important stuff is how system under test behaves, and it is
> not something tied to a single execution. What I mean is R8 kind of
> computation should better approximate the true percentile value than R1
> would, and it is the true value that is important to compare and report as
> a test result.
>

Will you submit a PR for that ? Before or after release of 3.3 ?
Thanks


>
> Vladimir
>



-- 
Cordialement.
Philippe Mouawad.

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