topic Re: how to access a summary statistic in the data step? in SAS Procedures

how to access a summary statistic in the data step?

eggman2001 — Sun, 09 Dec 2012 20:26:18 GMT

hello,

I know that with proc means I can find summary statistics for my data such as mean and N per variable. However, how can I then use these summary statistics in my data step, so that I can do something like find the distance of each observation from the mean, and then finally add up these distances.

i guess that sometimes i want to operate at the per observation level, and then sometimes i want to operate at the aggregate level, and i'm not quite sure what the approach is to switching back and forth between these. hope i'm making some sense.

Re: how to access a summary statistic in the data step?

Linlin — Sun, 09 Dec 2012 21:34:15 GMT

is the example helpful:

proc sql noprint;

select mean(height) into :mn

from sashelp.class;

quit;

data class;

set sashelp.class;

mean_height=&mn;

diff=height-&mn;

proc print;run;

Obs Name Sex Age Height Weight height diff

1 Alfred M 14 69.0 112.5 62.3368 6.6632

2 Alice F 13 56.5 84.0 62.3368 -5.8368

3 Barbara F 13 65.3 98.0 62.3368 2.9632

4 Carol F 14 62.8 102.5 62.3368 0.4632

5 Henry M 14 63.5 102.5 62.3368 1.1632

6 James M 12 57.3 83.0 62.3368 -5.0368

7 Jane F 12 59.8 84.5 62.3368 -2.5368

8 Janet F 15 62.5 112.5 62.3368 0.1632

9 Jeffrey M 13 62.5 84.0 62.3368 0.1632

10 John M 12 59.0 99.5 62.3368 -3.3368

11 Joyce F 11 51.3 50.5 62.3368 -11.0368

12 Judy F 14 64.3 90.0 62.3368 1.9632

13 Louise F 12 56.3 77.0 62.3368 -6.0368

14 Mary F 15 66.5 112.0 62.3368 4.1632

15 Philip M 16 72.0 150.0 62.3368 9.6632

16 Robert M 12 64.8 128.0 62.3368 2.4632

17 Ronald M 15 67.0 133.0 62.3368 4.6632

18 Thomas M 11 57.5 85.0 62.3368 -4.8368

19 William M 15 66.5 112.0 62.3368 4.1632

Re: how to access a summary statistic in the data step?

Reeza — Mon, 10 Dec 2012 03:52:38 GMT

Add the statistics back to your datastep. Search on the forum for many ways to do that. This is especially useful if you have statistics at a group level.

You can also look at some of the other stats that proc means gives you because they can be useful.

Re: how to access a summary statistic in the data step?

Ksharp — Mon, 10 Dec 2012 08:31:16 GMT

Or something like :

proc means;

output out=stat .....;

run;

data want;

set have;

if _n_ eq 1 then set stat ;

...........

Ksharp

Re: how to access a summary statistic in the data step?

Prit — Tue, 11 Dec 2012 11:45:25 GMT

You can add ods statement to collect statistics into new dataset which might be helpful to you.

ODS OUTPUT summary=summary_means; /* summary_means is the new dataset */

PROC MEANS DATA= <DATASET_NAME>;

VAR years_on_farm;

RUN;

ODS OUTPUT CLOSE;

Re: how to access a summary statistic in the data step?

cau83 — Thu, 13 Dec 2012 14:52:29 GMT

Instead of MEANS, use SQL to calculate statistics and then load them into macro variables that you reference in the data step.

eg.

PROC SQL noprint;

select mean(age), mean(weight) into :AverageAge, AverageWeight from your_data_set;

quit;

Data your_data_set2;

set your_data_set;

Age_variance=Age - &AverageAge;

Weight_variance=weight - &AverageWeight;

run;

Re: how to access a summary statistic in the data step?

Astounding — Thu, 13 Dec 2012 15:47:36 GMT

Forgive me if I need another cup of coffee on this one, but ...

If you compute the difference from the mean on each observation, then add up all the differences, doesn't the total have to be zero?

Re: how to access a summary statistic in the data step?

Reeza — Thu, 13 Dec 2012 19:05:43 GMT

No because of rounding/floating point error

Yes otherwise :smileysilly: