topic Calculating mean, mode, median and STD efficiently in SAS Procedures

Calculating mean, mode, median and STD efficiently

DrZenith — Thu, 22 Dec 2011 20:40:30 GMT

Hey guys...

I have a dataset like this,

Id Val1 val2 val3 val4 ......valn mean mode median std

1 10 20 30 40...

2 25 13 34 12....

For each row (for each id) i need to find out mean, mode, median and standard deviation and fill the values in the respective columns.

How do I do that efficiently?

Calculating mean, mode, median and STD efficiently

ballardw — Thu, 22 Dec 2011 22:13:59 GMT

3 of these are easy in a datastep;

data new;

set <your data>;

mean = mean (of val1-valn);

median=median (of val1-valn);

std = std (of val1-valn);

/* mode could have issues with tie breakers and such the following selects the first VALi */

/* and no claim to efficiency you may want to drop the c1 c2 i and such*/

array v val1-valn;

c2= 0;

do _i_ = 1 to (dim(v) -1);

c1= 1;

do _j_ = (_i_+1) to dim(v);

c1= c1 + (v[_i_]=v[_j_]);

end;

if c1 gt c2 then do;

c2=c1;

i=_i_;

end;

mode= v;

end;

run;

Calculating mean, mode, median and STD efficiently

art297 — Thu, 22 Dec 2011 23:02:25 GMT

The following doesn't account for tied modes either, but you may find it easier to code:

data have;

input Id Val1 val2 val3 val4 valn;

cards;

1 10 20 20 30 40

2 25 13 34 13 25

;

proc transpose data=have out=long;

var val:;

by id;

run;

proc summary data=long;

var col1;

by id;

output out=want mean=mean median=median std=std mode=mode;

run;

Calculating mean, mode, median and STD efficiently

DrZenith — Wed, 28 Dec 2011 18:04:35 GMT

Thanks guys, it helped!!