Hi, I don't have your original 'datei' table so I made some up in my 'datei' step. If you take the FORMAT 32.29 away the displayed values are 'displayed as rounded' but the internal value is unchanged. In the 'datei' step: The first thing to note is that decimal precision problems are being encountered: Input value 24.3999999999999 (13 decimal places ) and input values 24.39999999999999 (14 decimal places) are both displayed as 24.3999999999999 with 13 places! The effect is demonstrated again with 0.00...1 vs 0.09...1 (converts to 0.089...) In the 'test' step we see the following effects: 24.4 sets the flag vtdk* to 1 for all values (as per your original example) 23.39.. (decimal 13 places) sets vtdk4a to 1 but not vtdk4b. 23.39.. (decimal 14 places but only 13 displayed) sets vtdk4a and vtdk4b to 1! SAS cannot display  the 14 decimal places correctly but internally the value is closer to 14 decimal places and the round function still works!   The decision to round before every analysis will probably be based on the following factors: 1) data content / type of data 2) business area (rules and conventions) 3) desired outcome All of which will be influenced or overridden by the precision of SAS 8 byte numeric data! There are many SAS Papers on the subject of precision. One solution is to multiply decimals to whole numbers for calculation (whole number precsion is superior to decimal places) and then divide the end result. There is also a paper to implement a JAVA class (http://www2.sas.com/proceedings/forum2008/021-2008.pdf) in order to use 'BigDecimal'. Finally to answer your question: SAS always uses the internal value for calculation. The round function, when applied appropriately, will influence the calculation which can compensate for discrepancies between the displayed value and the internally held value. The round function will not rescue the situation where the internally held value has been altered (corrupted) due to 8 byte precision issues. Best Regards, Viele Grüße, Ian Sample Code and Data: data datei; /* Numeric Precision effects using SAS 9.3 on Windows 7 (64bit) - other Operating Systems may display different values */  format vitd 32.29; vitd = 24.4 ; OUTPUT; put vitd ; vitd = 24.3 ; OUTPUT; put vitd ; vitd = 24.3999999999999 ; OUTPUT; put vitd ; vitd = 24.39999999999999 ; OUTPUT; put vitd ; vitd = 24.5 ; OUTPUT; put vitd ; vitd = 1.00000000000000000000000000001 ; OUTPUT; put vitd ; vitd = 0.00000000000000000000000000001 ; OUTPUT; put vitd ; vitd = 0.09000000000000000000000000001 ; OUTPUT; put vitd ; run ; data test; set datei; format vitd 32.29; vitdk3=0; vitdk4a=0; vitdk4b=0; vitdk4c=0; vitdk5=0; if vitd=24.4 then vitdk3=1; /* 12 places */ if round(vitd,0.000000000001)=24.4 then vitdk4a=1; /* 13 places */ if round(vitd,0.0000000000001)=24.4 then vitdk4b=1; /* 14 places */ if round(vitd,0.00000000000001)=24.4 then vitdk4c=1; /* 15 places */ if round(vitd,0.000000000000001)=24.4 then vitdk5=1; * vitdk4 hat als einzige Kategoriale Variable korrekten Inhhalt:;   if vitdk4a=1 then do;     put vitd= ;   end;   if vitdk4b=1 then do;      put vitd= ;   end;   if vitdk4c=1 then do;      put vitd= ;   end; run; ... View more