Merging but keeping all observations?

sas

Solution

When you merge data sets in SAS that share variable names, the values from the data set listed on the right in the `merge` statement overwrite the values from data set to its left. In order to keep each value, you'd want to rename the variables before merging. You can do this in the `merge` statement by adding a `rename=` option after each data set.

If you want a single variable that represents whether a tobacco claim exists in any of the three variables, you could create a new variable using the `max` function to combine the three different values.

data tobaccoall;
  merge inpatient    (rename=(tobacco=tobacco_in))
        outpatient   (rename=(tobacco=tobacco_out))
        professional (rename=(tobacco=tobacco_pro));
  by rid;
  tobacco_any = max(tobacco_in,tobacco_out,tobacco_pro,0);
run;

Problem

I have three data sets of inpatient, outpatient, and professional claims. I want to find the number of unique people who have a claim related to tobacco use (1=yes tobacco, 0=tobacco) in ANY of these three data sets. Therefore, the data sets pretty much are all: ``` data inpatient; input Patient_ID Tobacco; datalines; 1 0 2 1 3 1 4 1 5 0 ; run; ``` I am trying to merge the inpatient, outpatient, and professional so that I am left with those patient ids that have a tobacco claim in any of the three data sets using: ``` data tobaccoall; merge inpatient outpatient professional; by rid; run; ``` However, it is overwriting some of the 1's with 0's in the new data set. How do I better merge the data sets to find if the patient has a claim in ANY of the datasets?

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