📊 PROC MEANS in SAS – A Complete Guide with Syntax, Options & Examples

📘 Introduction

The PROC MEANS procedure in SAS is one of the most frequently used procedures for generating descriptive statistics. It helps compute means, medians, standard deviations, minimums, maximums, and more for numeric variables.

This blog post explores everything about PROC MEANS:

• Syntax and arguments
• Available statistics
• Options and statements
• Multiple grouped examples
• Tips for better analysis

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🔧 Syntax of PROC MEANS

PROC MEANS <options>;
  VAR variable(s);
  CLASS variable(s);
  BY variable(s);
  OUTPUT OUT=dataset <output-options>;
RUN;

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🧾 Commonly Used Options in PROC MEANS

Option	Description
N	Count of non-missing values
MEAN	Average value
STD	Standard deviation
MIN	Minimum value
MAX	Maximum value
MEDIAN	Median value
SUM	Sum of values
MAXDEC=	Maximum number of decimals
DATA=	Specifies input dataset
NWAY	Forces output only for combinations of all class variables
CHARTYPE	Adds type variable in output
Q1, Q3	1st and 3rd quartiles

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🧠 Key Statements in PROC MEANS

Statement	Purpose
VAR	Specifies numeric variables to analyze
CLASS	Performs group-wise analysis (similar to GROUP BY)
BY	Performs BY-group processing (requires sorted data)
OUTPUT	Saves results to a new dataset

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🧪 PROC MEANS Examples

✅ Example 1: Basic Summary Statistics

proc means data=sashelp.class;
run;

Output: N, Mean, Std, Min, Max for all numeric variables.

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✅ Example 2: Specify Variables and Options

proc means data=sashelp.class mean std maxdec=2;
  var age height weight;
run;

Output: Mean and standard deviation for specified variables with 2 decimals.

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✅ Example 3: Using CLASS Statement

proc means data=sashelp.class n mean median maxdec=1;
  class sex;
  var height weight;
run;

Output: Summary by gender.

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✅ Example 4: Using BY Statement

proc sort data=sashelp.class out=sorted;
  by sex;
run;

proc means data=sorted n mean std;
  by sex;
run;

Note: BY requires pre-sorting.

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✅ Example 5: Saving Output to a Dataset

proc means data=sashelp.class n mean max min;
  var height weight;
  class sex;
  output out=class_summary mean=mean_height mean_weight;
run;

Output Dataset: class_summary with mean of height and weight by sex.

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✅ Example 6: Percentiles and Custom Statistics

proc means data=sashelp.class n mean median q1 q3;
  var weight;
run;

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📌 When to Use CLASS vs BY in PROC MEANS

Feature	CLASS	BY
Sorting	Not required	Requires sorting
Output	Summary by group	Separate table per group
Flexibility	More user-friendly for reporting	Ideal for structured data

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🧠 Tips for Using PROC MEANS Effectively

• Use MAXDEC= to format output.
• CLASS is easier to use than BY for grouped summaries.
• Combine with OUTPUT statement to reuse summary data.
• Filter data using WHERE before calling PROC MEANS.

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🧾 Summary Table

Feature	Description
Procedure Name	PROC MEANS
Primary Use	Descriptive statistics
Key Outputs	N, Mean, Std, Min, Max, Median, etc.
Common Options	MAXDEC=, NWAY, CHARTYPE
Supports Grouping	Yes – via CLASS and BY

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