From: | Ron <ronljohnsonjr(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: computing z-scores |
Date: | 2018-05-24 15:26:44 |
Message-ID: | a220c1bf-ab2b-d230-7526-442716f3db5f@gmail.com |
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Lists: | pgsql-general pgsql-hackers |
On 05/24/2018 10:15 AM, Martin Mueller wrote:
> You construct a z-score for a set of values by subtracting the average from the value and dividing the result by the standard deviation. I know how to do this in a two-step procedure. First, I compute the average and standard deviation. In a second run I use the formula and apply it to each value.
>
> Is there a way of doing this in a single-step procedure or can you chain the two parts together in one query? This goes beyond my SQL competence.
What about this?
SELECT value, (value - AVG(value))/stddev(value) as zvalue
FROM sometable
WHERE some conditions
GROUP by value
--
Angular momentum makes the world go 'round.
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