With Libre Office Calc, same result than with PostgreSQL : =CENTILE({1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;16;17;18;19;20;21;22;23;24;25;26;27;28;29;30}; 0.3333333333) gives 10.6666666657 (and NOT 10.5)
I didn't think so.
De: "PALAYRET Jacques" <jacques.palayret@meteo.fr> À: pgsql-general@lists.postgresql.org Envoyé: Mercredi 22 Avril 2020 10:15:26 Objet: Re: How do work tercile, percentile & funcion percentile_cont() ?
Of course, the same result with this table x(c1) for example :
SELECT percentile_cont(1./3) WITHIN GROUP (ORDER BY c1) FROM x ; percentile_cont ------------------ 10.6666666666667 (1 ligne)
SELECT percentile_cont(2./3) WITHIN GROUP (ORDER BY c1) FROM x ; percentile_cont ------------------ 20.3333333333333 (1 ligne)
De: "PALAYRET Jacques" <jacques.palayret@meteo.fr> À: pgsql-general@lists.postgresql.org Envoyé: Mercredi 22 Avril 2020 10:00:49 Objet: How do work tercile, percentile & funcion percentile_cont() ?
Hello,
From a table x(c1) containing 30 lines with integer values (column c1) from 1 to 30 :
SELECT percentile_cont(1./3) WITHIN GROUP (ORDER BY c1) FROM x ; percentile_cont ------------------ 10.6666666666667 (1 ligne) SELECT percentile_cont(2./3) WITHIN GROUP (ORDER BY c1) FROM x ; percentile_cont ------------------ 20.3333333333333 (1 ligne)
If ordering, the first 10 lines (c1 from 1 to 10) have ntile(3) OVER(ORDER BY c1) = 1, the 10 following lines (c1 from 11 to 20) have ntile(3) OVER(ORDER BY c1) = 2, the last 10 lines (c1 from 21 to 30) have ntile(3) OVER(ORDER BY c1) = 3. So, I though it should be : percentile_cont(1./3) = 10.5 (the arithmetic average between 10 et 11) and not 10.6666666666667 percentile_cont(2./3) = 20.5 (the arithmetic average between 20 et 21) and not 20.3333333333333
