EXACT
statisticoptions < / computationoptions > ;
The EXACT statement requests exact tests and confidence limits for selected statistics. The statisticoptions identify which statistics to compute, and the computationoptions specify options for computing exact statistics. See the section Exact Statistics for details.
Note: PROC FREQ computes exact tests by using fast and efficient algorithms that are superior to direct enumeration. Exact tests are appropriate when a data set is small, sparse, skewed, or heavily tied. For some large problems, computation of exact tests might require a considerable amount of time and memory. Consider using asymptotic tests for such problems. Alternatively, when asymptotic methods might not be sufficient for such large problems, consider using Monte Carlo estimation of exact pvalues. You can request Monte Carlo estimation by specifying the MC computationoption in the EXACT statement. See the section Computational Resources for more information.
The statisticoptions specify which exact tests and confidence limits to compute. Table 3.6 lists the available statisticoptions and the exact statistics that are computed. Descriptions of the statisticoptions follow the table in alphabetical order.
For oneway tables, exact pvalues are available for binomial proportion tests, the chisquare goodnessoffit test, and the likelihood ratio chisquare test. Exact (ClopperPearson) confidence limits are available for the binomial proportion.
For twoway tables, exact pvalues are available for the following tests: Pearson chisquare test, likelihood ratio chisquare test, MantelHaenszel chisquare test, Fisher’s exact test, JonckheereTerpstra test, and CochranArmitage test for trend. Exact pvalues are also available for tests of the following statistics: Pearson correlation coefficient, Spearman correlation coefficient, Kendall’s taub, Stuart’s tauc, Somers’ , Somers’ , simple kappa coefficient, and weighted kappa coefficient.
For tables, PROC FREQ provides the exact McNemar’s test, exact confidence limits for the odds ratio, and Barnard’s unconditional exact test for the risk (proportion) difference. PROC FREQ also provides exact unconditional confidence limits for the risk difference and for the relative risk (ratio of proportions). For stratified tables, PROC FREQ provides Zelen’s exact test for equal odds ratios, exact confidence limits for the common odds ratio, and an exact test for the common odds ratio.
Most of the statisticoption names listed in Table 3.6 are identical to the corresponding option names in the TABLES and OUTPUT statements. You can request exact computations for groups of statistics by using statisticoptions that are identical to the TABLES statement options CHISQ, MEASURES, and AGREE. For example, when you specify the CHISQ statisticoption in the EXACT statement, PROC FREQ computes exact pvalues for the Pearson chisquare, likelihood ratio chisquare, and MantelHaenszel chisquare tests for twoway tables. You can request an exact test for an individual statistic by specifying the corresponding statisticoption from the list in Table 3.6.
You must use a TABLES statement with the EXACT statement. If you use only one TABLES statement, you do not need to specify the same options in both the TABLES and EXACT statements; when you specify a statisticoption in the EXACT statement, PROC FREQ automatically invokes the corresponding TABLES statement option. However, when you use an EXACT statement with multiple TABLES statements, you must specify options in the TABLES statements to request statistics. PROC FREQ then provides exact tests or confidence limits for those statistics that you also specify in the EXACT statement.
Table 3.6: EXACT Statement Statistic Options
Statistic Option 
Exact Statistics 

McNemar’s test (for tables), simple kappa test, 

weighted kappa test 

Barnard’s test (for tables) 

Binomial proportion tests for oneway tables 

Chisquare goodnessoffit test for oneway tables; 

Pearson chisquare, likelihood ratio chisquare, and 

MantelHaenszel chisquare tests for twoway tables 

Confidence limits for the common odds ratio, 

common odds ratio test (for tables) 

Zelen’s test for equal odds ratios (for tables) 

Fisher’s exact test 

JonckheereTerpstra test 

Test for the simple kappa coefficient 

Test for Kendall’s taub 

Likelihood ratio chisquare test (oneway and twoway tables) 

McNemar’s test (for tables) 

Tests for the Pearson correlation and Spearman correlation, 

confidence limits for the odds ratio (for tables) 

MantelHaenszel chisquare test 

Confidence limits for the odds ratio (for tables) 

Pearson chisquare test (oneway and twoway tables) 

Test for the Pearson correlation coefficient 

Confidence limits for the relative risk (for tables) 

Confidence limits for the proportion difference (for tables) 

Test for the Spearman correlation coefficient 

Test for Somers’ 

Test for Somers’ 

Test for Stuart’s tauc 

CochranArmitage test for trend 

Test for the weighted kappa coefficient 
You can specify the following statisticoptions in the EXACT statement.