I have noticed that the Cochran-Armitage Test for Trend gives different results when an interval variable is grouped by proc format compared to recoding. For example: proc format; value EngineSizeFmt        low -<  3  = "0-3"         3 -<  5 = "3-4"        5 -<  9= "5-8"        ; run; proc freq data=sashelp.cars; where origin in("Europe" "USA"); tables EngineSize*origin /trend chisq nopercent norow;    format EngineSize EngineSizeFmt.; run; data work.cars; set sashelp.cars; if EngineSize lt 3 then esize=1; if EngineSize ge 3 and EngineSize lt 5 then esize=2; if EngineSize ge 5 then esize=3; run; proc freq data=work.cars; where origin in("Europe" "USA"); tables ESize*origin /trend chisq nopercent norow;  run;   The frequencies and chi-square test are the same, the trend test is different. Any thoughts? Which should be used? ... View more