> Does anyone have a handy function for calculating the Median of data ??
It
> seems like it should be simple ...but
Kevin,
Maybe not as simple as you think. :)
Here's an example in SQL. You may want to dig through the
archives, as this was discussed at some lenght a few months
ago.
Ross may remember it.
Jared
-- middle value is chosen as median when there is an
-- odd number of values
-- average of 2 middle values is chosen median
-- when there is an even number of values
drop table median;
create table median ( value number );
insert into median values ( 111 );
insert into median values ( 543 );
insert into median values ( 566 );
insert into median values ( 643 );
insert into median values ( 456 );
insert into median values ( 98 );
insert into median values ( 877 );
insert into median values ( 867 );
insert into median values ( 687 );
insert into median values ( 6886 );
-- uncomment this row for an odd number of values
--insert into median values ( 982 );
commit;
break on report
compute avg label 'Median' of value on report
column value heading 'values|averaged|in median'
select
rownum,
value
from (
select value
from median
where value is not null
union
select 1 from dual where 1=2
)
group by value, rownum
having rownum >= (
select decode( mod(total_freq,2),
1,trunc(total_freq/2 + 1),
0,trunc(total_freq/2)
)
from (
select count(*) total_freq
from median
where value is not null
)
)
and rownum <= (
select decode( mod(total_freq,2),
1,trunc(total_freq/2 + 1),
0,trunc(total_freq/2 + 1)
)
from (
select count(*) total_freq
from median
where value is not null
)
)
/
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