Post on 21-Dec-2015
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 testsonly 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 ThompsonResearch Methods Unit, Department of Medicine, Dalhousie University902-473 -2094kara.thompson@dal.ca
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