A macro to execute PROC TTEST for multiple binary grouping variables in SAS (and sorting t-test statistics by their absolute values)

In SAS, you can perform PROC TTEST for multiple numeric variables in the same procedure.  Here is an example using the built-in data set SASHELP.BASEBALL; I will compare the number of at-bats and number of walks between the American League and the National League.

proc ttest
     data = sashelp.baseball;
     class League;
     var nAtBat nBB; 
     ods select ttests;
run;

Here are the resulting tables.

Method	Variances	DF	t Value	Pr > |t|
Pooled	Equal	320	2.05	0.0410
Satterthwaite	Unequal	313.66	2.06	0.04

Method	Variances	DF	t Value	Pr > |t|
Pooled	Equal	320	0.85	0.3940
Satterthwaite	Unequal	319.53	0.86	0.3884

 

What if you want to perform PROC TTEST for multiple grouping (a.k.a. classification) variables?  You cannot put more than one variable in the CLASS statement, so you would have to run PROC TTEST separately for each binary grouping variable.  If you do put LEAGUE and DIVISION in the same CLASS statement, here is the resulting log.

1303 proc ttest
1304 data = sashelp.baseball;
1305 class league division;
 --------
 22
 202
ERROR 22-322: Expecting ;.
ERROR 202-322: The option or parameter is not recognized and will be ignored.
1306 var natbat;
1307 ods select ttests;
1308 run;

 

There is no syntax in PROC TTEST to use multiple grouping variables at the same time, so this tutorial provides a macro to do so.  There are several nice features about my macro:

1. It allows you to use multiple grouping variables at the same time.
2. It sorts the t-test statistics by their absolute values within each grouping variable.
3. It shows the name of each continuous variable in the output table, unlike the above output.

Here is its basic skeleton.

Use ODS EXCLUDE ALL to suppress printing output in SAS while producing output data sets

I regularly produce output data sets from a SAS procedure, such as getting the variable names from a data set in PROC CONTENTS.  In these instances, I often wish to suppress any printing of the output in HTML or TXT.  Such printing of the results is often unnecessary, and it can cost a lot of time and memory.

Some SAS procedures have the NOPRINT option that suppresses the printing of output, but this is limiting in several ways:

1. Some SAS procedures do NOT have the NOPRINT option.  PROC TTEST is a prominent example.  I checked the high-performance procedures like PROC HPFOREST (random forest) and PROC HPSVM (support vector machine), and I could not find the NOPRINT option for these procedures.
2. I cannot use ODS OUTPUT to produce output data sets while invoking the NOPRINT option.  Here is an example.

Career Panel at the 2018 Canadian Statistics Student Conference – McGill University, Montreal, Quebec

I will speak on the career-advice panel at the 2018 Canadian Statistics Student Conference.  It will be held on Saturday, June 2, at McGill University.

If you will attend this conference or the subsequent Annual Meeting of the Statistical Society of Canada, then I strongly recommend students to read my following advice articles in advance.

• How to Find a Job in Statistics – Advice for Students and Recent Graduates
• A Comprehensive Guide for Public Speaking at Scientific Conferences
• Maximizing Your Learning Potential at Professional Conferences – A Detailed Guide