Hi Helen,
Assuming you want to calculate stddev_samp, Spark correctly points STDDEV
to STDDEV_SAMP.
In below replace sales with your table name and AMOUNT_SOLD with the column
you want to do the calculation
SELECT
SQRT((SUM(POWER(AMOUNT_SOLD,2))-(COUNT(1)*POWER(AVG(AMOUNT_SOLD),2)))/(COUNT(1)-1))
AS MYSTDDEV,
STDDEV(amount_sold) AS STDDEV,
STDDEV_SAMP(amount_sold) AS STDDEV_SAMP,
STDDEV_POP(amount_sold) AS STDDEV_POP
from sales;
for me it returned
+--------------------+---------------------+--------------------+---------------------+--+
| mystddev | stddev | stddev_samp |
stddev_pop |
+--------------------+---------------------+--------------------+---------------------+--+
| 260.7270919450411 | 260.7270722861637 | 260.7270722861637 |
260.72704617042166 |
+--------------------+---------------------+--------------------+---------------------+--+
HTH
Mich Talebzadeh,
Distinguished Technologist, Solutions Architect & Engineer
London
United Kingdom
view my Linkedin profile
<https://www.linkedin.com/in/mich-talebzadeh-ph-d-5205b2/>
https://en.everybodywiki.com/Mich_Talebzadeh
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On Tue, 19 Sept 2023 at 13:14, Helene Bøe <helene.b...@hydro.com.invalid>
wrote:
> Hi!
>
>
>
> I am applying the stddev function (so actually stddev_samp), however when
> comparing with the sample standard deviation in Excel the resuls do not
> match.
>
> I cannot find in your documentation any more specifics on how the sample
> standard deviation is calculated, so I cannot compare the difference toward
> excel, which uses
>
> .
>
> I am trying to avoid using Excel at all costs, but if the stddev_samp
> function is not calculating the standard deviation correctly I have a
> problem.
>
> I hope you can help me resolve this issue.
>
>
>
> Kindest regards,
>
>
>
> *Helene Bøe*
> *Graduate Project Engineer*
> Recycling Process & Support
>
> M: +47 980 00 887
> helene.b...@hydro.com
> <https://intra.hydro.com/EPiServer/CMS/Content/en/%2c%2c9/?epieditmode=False>
>
> Norsk Hydro ASA
> Drammensveien 264
> NO-0283 Oslo, Norway
> www.hydro.com
> <https://intra.hydro.com/EPiServer/CMS/Content/en/%2c%2c9/?epieditmode=False>
>
>
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