On Tue, Dec 10, 2013 at 11:02 AM, Greg Stark <st...@mit.edu> wrote: > > On 10 Dec 2013 08:28, "Albe Laurenz" <laurenz.a...@wien.gv.at> wrote: >> >> >> Doesn't all that assume a normally distributed random variable? > > I don't think so because of the law of large numbers. If you have a large > population and sample it the sample behaves like a normal distribution when > if the distribution of the population isn't.
No, the large population says that if you have an AVERAGE of many samples of a random variable, the random variable that is the AVERAGE behaves like a normal. The variable itself doesn't. And for n_distinct, you need to know the variable itself. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
