PROC FREQ
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What good is Proc FREQ
• It Counts! Answers question how many
• Display data (error checks), descriptive
• Analyze categorical data, statistical
• It is fast and easy
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Syntax
PROC FREQ;
BY variables;
EXACT statistic – options </computation-options>;
OUTPUT <OUT=SAS-data-set> output-options;
TABLES requests </options>;
TEST options;
WEIGHT variable </option>;
RUN;
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Just How Simple is it?
Proc freq;
Run;
Proc freq data=mydata1;
Tables _all_;
or Tables _CHAR_;
Run;
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Options
PROC FREQ;
NLEVELS – Number of variable levels
new back in version 9
ORDER=
– DATA|FORMATTED|FREQ|INTERNAL
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Formatting Options
TABLES variables/ options;
• 1-way, 2-way to n–way tables
• MISSPRINT, MISSING
• CROSSLIST, LIST,
• NOCOL, NOCUM, NOROW, NOFREQ, CUMCOL
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Example
Proc freq data=mydata1;
Tables sex*health/nocum norow nopercent;
Run;
Proc freq data=mydata1;
Tables sex*health/crosslist;
Run;
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Proc freq data=mydata1;
tables region*sex*health/nocum norow nopercent;
run;
Proc sort data=mydata1;
by region;
run;
Proc freq data=mydata1;
by region;
tables sex*health/nocum norow nopercent;
run;
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Statistical Computations
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Statistical Computations
Proc freq data=mydata1;
Where racer ne 3;/*excludes where race=other*/
Tables sex*racer/chisq agree measures nowarn;
Run;
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Statistical Computations
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EXACT
• Alternative to asymptotic p-values
(sparse, skewed or heavily tied data)
• Computed using network algorithms
• Monte Carlo estimation also available
POINT – exact probability that test statistic equals the
observed value
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New in SAS 9.3
•Exact conditional Confidence Limits for Risk
Difference and Relative Risk
•Maxlevels
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New in SAS 9.4
• MIDP - mid-p-values for exact tests
only half of probability of observed sample is included in tail
• Score confidence limits for Odds ratio and
Relative Risk
• Supports Baher, exact mid-p, likelihood ratio
and logit binomial confidence limits
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Kara Thompson
Research Methods Unit,
Department of Medicine, Dalhousie University
902-473 -2094
[email protected]
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