I need to search for big differences between values.
[...]
Hi,
from an SQL point of view this is not difficult, but you need to
carefully define a criteria for the outliers.
For example, to find values that are more than a standard deviation
away from the mean, do something like this:
chris=# select * from val;
x
-------
20
21
21.5
30
28
46392
46393
40
(8 rows)
chris=# select * from val where x > (select avg(x) + stddev(x) from val) or x < (select avg(x) - stddev(x) from val);
x
-------
46392
46393
(2 rows)
Try with n*stddev(x) for n = 2, 3, 4, 5, ... to see
if you can get to your outliers...
Bye,
Chris.
