On Thu, Dec 3, 2015 at 1:30 PM, Olga Botvinnik <obotvinn@ucsd.edu> wrote:
Ah okay. I find the langauge and punctuation unclear. What about rewording the documentation to "Survival function (sometimes more accurate than the alternate definition of 1-cdf)." or equivalent? I'm happy to submit a PR
Please do. documentation improvements are always useful. This phrasing is most likely ancient. BTW: [ci skip] in the commit message avoids a TravisCI run which is not needed for pure documentation changes. Josef
On Thu, Dec 3, 2015 at 10:18 AM <josef.pktd@gmail.com> wrote:
On Thu, Dec 3, 2015 at 1:04 PM, Olga Botvinnik <obotvinn@ucsd.edu> wrote:
For the random variables in scipy.stats, I have a question about the documentation. Does the statement "Survival function (1-cdf — sometimes more accurate)." mean:
1. Survival function (also defined as 1-cdf, and the survival function version is sometimes more accurate). -- or -- 2. Survival function (also defined as 1-cdf, and 1-cdf is sometimes more accurate).
the second part means: using sf is in many cases more accurate than 1 - cdf This applies when we want to evaluate probabilities in the right tail.
1 - norm.cdf(20) is worse than sf(20)
For some distribution there is no explicit sf implementation, then internally it's also sf = 1 - cdf by default, and accuracy can be low far in the tail.
Josef
Thanks! Olga
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