R vs SAS Paired T-Test

Paired t-test Comparison

The following table shows the types of Paired t-test analysis, the capabilities of each language, and whether or not the results from each language match.

Analysis	Supported in R	Supported in SAS	Results Match	Notes
Paired t-test, normal data	Yes	Yes	Yes	In Base R, use paired = TRUE on t.test() function
Paired t-test, lognormal data	Maybe	Yes	NA	May be supported by envstats package

Comparison Results

Normal Data

Here is a table of comparison values between t.test(), proc_ttest(), and SAS PROC TTEST:

Statistic	t.test()	proc_ttest()	PROC TTEST	Match	Notes
Degrees of Freedom	11	11	11	Yes
t value	-1.089648	-1.089648	-1.089648	Yes
p value	0.2992	0.2992	0.2992	Yes

Lognormal Data

Since there is currently no known support for lognormal t-test in R, this comparison is not applicable.

Summary and Recommendation

For normal data, the R paired t-test capabilities are comparable to SAS. Comparison between SAS and R show identical results for the datasets tried. The procs package proc_ttest() function is very similar to SAS in the syntax and output produced. proc_ttest() also supports by groups, where t.test() does not.

For the lognormal version of the t-test, it does not appear to be supported in the stats or procs package. It may be supported in the envstats package. More exploration is needed to determine whether this package will produce the expected results, and whether the results will match SAS.

References

R t.test() documentation: https://www.rdocumentation.org/packages/stats/versions/3.6.2/topics/t.test

R proc_ttest() documentation: https://procs.r-sassy.org/reference/proc_ttest.html

SAS PROC TTEST Paired analysis documentation: https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_ttest_syntax08.htm