In this task, you will use the PROC MEANS procedure to check for missing, minimum, and maximum values of continuous variables, and the PROC FREQ procedure to look at the frequency distribution of categorical variables in your analytic dataset. The output from these procedures provides the number and frequency of missing values for each variable listed in the procedure statement. In this example, you will check for missing values as well as minimum and maximum values for the urinary phthalate metabolite and urinary creatinine variables.
The steps below assume that you are already familiar with the SAS code used to identify and recode missing data in NHANES datasets. If you need more detailed instructions, please review the Clean & Recode Data module in the Continuous NHANES Web Tutorial before continuing. |
proc means data =Phthalate N Nmiss min max maxdec = 2; where WTSPH6YR> 0; var URDMHPLC URXMHP; run ; |
proc freq data =Phthalate; where WTSPH6YR> 0; table URDMHPLC/ missing ;
proc freq data =Phthalate; where WTSPH6YR> 0; table SDDSRVYR*URDMHPLC/ missing list ; run ; |