Identifying number participants by subtracting date

[hjjijkkl]

I am trying to find the number of participants between specific time period. How would be able to calculate that in SAS. For example,  How can determine the total number of hospital visitors from 10/20/2018 - until "today" who has positive flu test  from the table below? Please help! Thank you!

ID	date	Flu_test
1	2/8/2019	negative
2	6/12/2021	positive
3	7/10/2017	positive
4	6/23/2020	.
5	8/15/2019	positive
6	8/24/2017	negative
7	12/20/2020	positive

the outcome will be

3 = positive

1 = negative 

[PaigeMiller]

Please post your data in usable form (instructions)

[ballardw · Accepted solution]

If your date is an actual SAS date value then you can use a WHERE clause to identify records after a specific date by:

Where date > "20OCT2018"d;

The literal date must be in a Date9. (or date7. or other format with DDMONYY) in quotes and followed by the letter d to tell SAS you intend the value to be treated as a date.

Note the data step to create actual data that can be used with code. Please do so for future examples and paste into a text box opened with the </>  (shown) or the "running man" icon that appears above the message window.

data have;
   input ID $ date :mmddyy10. Flu_test $;
   format date mmddyy10.;
datalines;
1 2/8/2019 negative
2 6/12/2021 positive
3 7/10/2017 positive
4 6/23/2020 .
5 8/15/2019 positive
6 8/24/2017 negative
7 12/20/2020 positive
;


proc freq data=have;
   Where date > "20OCT2018"d; 
   tables flu_test;
run;

If your variable Date is not numeric with a date format applied that will be the first step: get a date value.