 |
 |
Archives of the TeradataForum
Message Posted: Sat, 23 Dec 2006 @ 13:42:21 GMT
| Subj: | | Re: Standard deviation for multiple columns |
| |
| From: | | Victor Sokovin |
| | I don't think there is a Teradata equivalent. Both stddev_samp and stddev_pop are Teradata "aggregate" functions, while the STD data step
function in SAS operates on *values*, not columns. In other words, std(x,y) returns the standard deviation of the two current values of x and y
*for each row*, i.e.: | |
> proc sql;
> select x, y, std(x,y) as std_x_y
> from mytable;
> quit;
> x y std_x_y
> -------- ------- --------
> 1 2 0.707107
> 2 3 0.707107
> 4 5 0.707107
> 6 7 0.707107
| | If you REALLY need to find the standard deviation of different columns taken as one series, I suppose you can UNION each column into one
derived table, such as: | |
> Select stddev_samp(x)
> >From (select x from table union all select y from table)
Bob probably did not notice my question or I missed out on his reply but if the std(x,y) only calculates the standard deviation between two
numbers then Teradata has an easy equivalent:
std(x,y) = abs(y-x)/sqrt(2).
Regards,
Victor
| |
