topic Re: creating dummy variables and assigning flags in SAS Procedures

creating dummy variables and assigning flags

swar — Fri, 21 Apr 2017 02:53:24 GMT

Hi. I have to create five dummy variables by combining 2 existing tables and assign flags 1 and 0 based on the following conditions.

Column	Set to 1 if and only if:
flg_If	Diagnosed by Infection
flg_rf	Diagnosed by respiratory infection
flg_30d	Patient died within 30 days of discharge(I have dates in another table admission_dt and discharge_dt)
flg_60d	Patient died in 60 days
flg_x_30d	Either flg_30d or flg_rf are set to 1

Please help... How to create new columns and assign flags at the same time?

Re: creating dummy variables and assigning flags

PGStats — Fri, 21 Apr 2017 02:59:34 GMT

Please provide meaningful examples of the two tables.

Re: creating dummy variables and assigning flags

swar — Fri, 21 Apr 2017 03:19:15 GMT

The tables are as follows

patientid claim_id date_of_admission date_of_discharge death_date code

1 1 12/1/2011 1/2/2012 1/31/2012 P2

2 2 12/1/2010 2/2/2012 2/4/2012 R3

Second table

Code Description

P2 Infection

R3 Respiratory infection

Now I should create a combined table containing the following columns

patient_id claim_id and the below five dummy variables by combining 2 existing tables and assign flags 1 and 0 based on the following conditions.

Column	Set to 1 if and only if:
flg_If	Diagnosed by Infection
flg_rf	Diagnosed by respiratory infection
flg_30d	Patient died within 30 days of discharge(I have dates in another table admission_dt and discharge_dt)
flg_60d	Patient died in 60 days
flg_x_30d	Either flg_30d or flg_rf are set to 1

Re: creating dummy variables and assigning flags

Reeza — Fri, 21 Apr 2017 03:50:27 GMT

Your sample data should include at minimum 1 of each case of flag, bonus if you have all 2 way, 3 way and 4 way flags and cases where no flags are set.

This will allow you to test your logic thoroughly.

Re: creating dummy variables and assigning flags

swar — Fri, 21 Apr 2017 11:26:59 GMT

I have given a sample table.

So, how do I create those 5 new columns as assign flag variables to them using proc sql?

Please help

Re: creating dummy variables and assigning flags

PGStats — Fri, 21 Apr 2017 22:06:55 GMT

Something like this?

data have;
input patientid claim_id   
    (date_of_admission   date_of_discharge  death_date) (:mmddyy10.) code $;
format date_of_admission   date_of_discharge  death_date yymmdd10.;
datalines;
1  1  12/1/2011 1/2/2012 1/31/2012  P2
2  2  12/1/2010  2/2/2012  2/4/2012  R3
;

data want;
set have;
flg_rf = code in ("R3");
flg_lf = code in ("P2", "R3");
flg_30d = intck("day", date_of_discharge, death_date) <= 30;
flg_60d = intck("day", date_of_discharge, death_date) <= 60;
flg_x_30d = flg_30d or flg_rf;
run;

Re: creating dummy variables and assigning flags

swar — Fri, 21 Apr 2017 22:52:19 GMT

Thanks. But How to set 0 and 1 values to these?

Re: creating dummy variables and assigning flags

Reeza — Sat, 22 Apr 2017 01:53:51 GMT

@swar wrote:
Thanks. But How to set 0 and 1 values to these?

Run the code and check the output.

Re: creating dummy variables and assigning flags

PGStats — Sat, 22 Apr 2017 02:09:43 GMT

SAS sets the value to 0 for FALSE and 1 for TRUE. So

flg_rf = code in ("R3");

will assign the value 1 to flg_rf if code is "R3" and 0 otherwise.

Re: creating dummy variables and assigning flags

swar — Sat, 22 Apr 2017 19:33:26 GMT

I have another doubt.. Can I write flag variables using proc sql code? If yes how?

Thanks a lot for being patient.

Re: creating dummy variables and assigning flags

Reeza — Sat, 22 Apr 2017 20:22:58 GMT

@swar wrote:

I have another doubt.. Can I write flag variables using proc sql code? If yes how?

Thanks a lot for being patient.

That's not a doubt, it's a question.

Yes you can, the exact same way in fact but using the appropriate SQL statements.

proc sql;
create table want as
select *, sex='F' as indicator_sex
from sashelp.class;
quit;

Re: creating dummy variables and assigning flags

swar — Sat, 22 Apr 2017 21:00:43 GMT

This code is not working.

I have used it like this

proc sql;

create table Table3 as

select *, condition= 'R3' as flg_rf

from table2;

select * from Table3;

I have to create 5 dummy variables..

Re: creating dummy variables and assigning flags

PGStats — Sat, 22 Apr 2017 21:31:05 GMT

Check the Log window where SAS tells you why it "is not working".

Re: creating dummy variables and assigning flags

swar — Sat, 22 Apr 2017 22:35:55 GMT

Thank you! But there are so many errors in flag creation.

My date columns have null values ie missing values in the table..

1.When I use this command with proc sql,

intck('day', dt_discharge,dt_death) le 30 as flg_30d ,

when dt_death has missing values it should give 0 as output but it is returning 1.

2. Also, flg_30d or flg_rf as flg_x_30d cannot be used as such in proc sql right?

I suppose I should use the entire expressions intck('day', dt_discharge,dt_death) le 30 or intck('day', date_of_discharge, death_date) le 60 as flg_60d as flg_x_30d in proc sql to flag those variables.

3. There is another expression in intck('day', dt_discharge,dt_admission) where I have to find the difference between discharge date and second successive admission date to hospital. So how would I find second instance of dt_admission ?

kindly help....

Re: creating dummy variables and assigning flags

PGStats — Sun, 23 Apr 2017 00:57:39 GMT

1) Replace the missing death date with a much later date

intck('day', dt_discharge,coalesce(dt_death,"31dec2100"d)) le 30 as flg_30d ,

2) Refer to previously calculated values with the keyword calculated

calculated flg_30d or calculated flg_rf as flg_x_30d

3) More detail needed. Where is that re-admission date in your data? I suggest that you post as a new question.