Re: gaussian distribution pgbench

From: Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
To: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: gaussian distribution pgbench
Date: 2014-07-03 10:01:35
Message-ID: 53B529FF.1000704@archidevsys.co.nz
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On 03/07/14 20:58, Fabien COELHO wrote:
>
> Hello Gavin,
>
>>> decile percents: 69.9% 21.0% 6.3% 1.9% 0.6% 0.2% 0.1% 0.0% 0.0% 0.0%
>>> probability of fist/last percent of the range: 11.3% 0.0%
>
>> I would suggest that probabilities should NEVER be expressed in
>> percentages! As a percentage probability looks weird, and is never
>> used for serious statistical work - in my experience at least.
>>
>> I think probabilities should be expressed in the range 0 ... 1 - i.e.
>> 0.35 rather than 35%.
>
> I could agree about the mathematics, but ISTM that "11.5%" is more
> readable and intuitive than "0.115".
>
> I could change "probability" and replace it with "frequency" or maybe
> "occurence", what would you think about that?
>

You may well be hitting a situation, where you meet opposition whatever
you do! :-)

"frequency" implies a positive integer (though "relative frequency"
might be okay) - and if you use "occurrence", someone else is bound to
complain...

Though, I'd opt for "relative frequency", if you can't use values in the
range 0 ... 1 for probabilities, if %'s are used - so long as it does
not generate a flame war.

I suspect it may not be worth the grief to change.

Cheers,
Gavin

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