Analyzing Data with PROC MEANS in SAS

Welcome back to Mindful Data Minds! In this session, we’ll explore one of the most commonly used procedures in SAS — PROC MEANS. It’s a powerful tool for calculating descriptive statistics such as mean, median, count, sum, percentiles, quartiles, standard deviation, variance, and even sample t-tests.

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What You Will Learn

How to use PROC MEANS for descriptive statistics.
How to select specific variables and statistics.
The difference between CLASS and BY.
How to save results into a dataset with OUTPUT.
How to interpret the _TYPE_ variable in grouped outputs.

General Syntax

proc means data=&lt;dataset>;
   by &lt;variable>;
   class &lt;variable>;
   var &lt;numeric variables>;
   output out=&lt;dataset> &lt;statistics>;
run;

DATA= → Input dataset
BY / CLASS → Grouping variables
VAR → Numeric variables to analyze
OUTPUT → Save results into a dataset

Default Behavior

By default, PROC MEANS calculates for all numeric variables:

Number of observations (N)
Mean
Standard deviation
Minimum
Maximum

proc means data=sashelp.cars;
run;

Produces summary statistics for all numeric variables in sashelp.cars

Selecting Specific Variables

You can restrict analysis to certain variables:

proc means data=sashelp.cars;
   var msrp invoice enginesize;
run;

Only MSRP, Invoice, and Engine Size are analyzed.

Selecting Specific Statistics

You can choose which statistics to display:

proc means data=sashelp.cars n mean;
   var msrp invoice enginesize;
run;

Displays only N and Mean.

Grouping Data: CLASS vs. BY

CLASS Statement

proc means data=sashelp.cars;
   class origin;
   var msrp invoice enginesize;
run;

Produces one table with statistics grouped by Origin.

BY Statement

proc sort data=sashelp.cars out=a;
   by origin;
run;

proc means data=a;
   by origin;
   var msrp invoice enginesize;
run;

Produces separate tables for each Origin.

Note: Data must be sorted before using BY.

Difference:

CLASS → One combined table.
BY → Multiple separate tables.

Saving Results with OUTPUT

You can save results into a dataset:

proc means data=sashelp.cars n mean median min max;
   class origin;
   var msrp invoice enginesize;
   output out=cars_class autoname;
run;

Creates a dataset cars_class with statistics for each variable, automatically named (e.g., msrp_mean, invoice_min).

Understanding TYPE Variable

When using CLASS:

_TYPE_=0 → Overall statistics (no grouping).
_TYPE_=1 → Grouped statistics (by Origin).

With BY, only grouped statistics are produced.

Next Step

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Proc Format

Proc Summary

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