topic Create flag for true positives using flag and time from record(s) above in New SAS User

Create flag for true positives using flag and time from record(s) above

bel2806 — Fri, 17 Apr 2020 20:21:58 GMT

I am interested in creating a flag for whether or not an alarm was a true positive. We consider the alarm a true positive if the 'predictiveAlarm' occurs (=1) within 1 hour prior to the first time an alarm goes off each night. I.e., row #9 would be a true positive because the predictive alarm went off 20 minutes prior (row #7).

What the data looks like:

Obs	PtID	deviceDt	deviceTm	alarm	predictiveAlarm
1	1111	9-Sep-17	0:18	0	0
2	1111	9-Sep-17	0:28	0	0
3	1111	9-Sep-17	1:58	0	0
4	1111	9-Sep-17	2:08	0	1
5	1111	9-Sep-17	2:18	0	1
6	1111	9-Sep-17	2:28	0	1
7	1111	9-Sep-17	2:38	0	1
8	1111	9-Sep-17	2:48	0	0
9	1111	9-Sep-17	2:58	1	0
10	1111	9-Sep-17	3:08	1	0
11	1111	9-Sep-17	3:18	1	0

Re: Create flag for true positives using flag and time from record(s) above

ballardw — Fri, 17 Apr 2020 21:12:18 GMT

Your example data show 4 potential candidates for comparing the time when PredictiveAlarm=1. In the shown cases all of them would be within an hour but what if that were not the case? Would earliest, latest or some thing in between be used for the time comparison?

I would suggest creating a single SAS datetime valued variable instead of date and time since that will considerably simplify comparing times across midnight. It is not clear to me whether your date or time values are actually SAS date and Time values.

You should provide example data in the form of a data step as that resolves such questions. Instructions here: https://communities.sas.com/t5/SAS-Communities-Library/How-to-create-a-data-step-version-of-your-data-AKA-generate/ta-p/258712 will show how to turn an existing SAS data set into data step code that can be pasted into a forum code box using the <> icon or attached as text to show exactly what you have and that we can test code against.

You didn't state it explicitly but I would assume that this has to be within each value for Ptid, correct?

And for a last question, what is the desired output appearance for the comparison?

Re: Create flag for true positives using flag and time from record(s) above

novinosrin — Fri, 17 Apr 2020 22:29:15 GMT

HI @bel2806 Assuming I understand your requirement


data have;
input Obs	PtID	deviceDt :date9.	deviceTm :time5.	alarm	predictiveAlarm;
format deviceDt date9.	deviceTm time5.;
cards;
1	1111	9-Sep-17	0:18	0	0
2	1111	9-Sep-17	0:28	0	0
3	1111	9-Sep-17	1:58	0	0
4	1111	9-Sep-17	2:08	0	1
5	1111	9-Sep-17	2:18	0	1
6	1111	9-Sep-17	2:28	0	1
7	1111	9-Sep-17	2:38	0	1
8	1111	9-Sep-17	2:48	0	0
9	1111	9-Sep-17	2:58	1	0
10	1111	9-Sep-17	3:08	1	0
11	1111	9-Sep-17	3:18	1	0
;

data want;
 do _n_=-999 by 0 until(last.deviceDt);
  set have;
  by ptid deviceDt;
  if predictiveAlarm then _t=deviceTm;
  if not _a and alarm then do;
   _a=deviceTm;
   if 0<=intck('min',_t,_a)<=60 then _n_=_t;
  end;
 end;
 do until(last.deviceDt);
  set have;
  by ptid deviceDt;
  flag=deviceTm=_n_;
  output;
 end;
 drop _:;
run;

proc print noobs;run;

Obs	PtID	deviceDt	deviceTm	alarm	predictiveAlarm	flag
1	1111	09SEP2017	0:18	0	0	0
2	1111	09SEP2017	0:28	0	0	0
3	1111	09SEP2017	1:58	0	0	0
4	1111	09SEP2017	2:08	0	1	0
5	1111	09SEP2017	2:18	0	1	0
6	1111	09SEP2017	2:28	0	1	0
7	1111	09SEP2017	2:38	0	1	1
8	1111	09SEP2017	2:48	0	0	0
9	1111	09SEP2017	2:58	1	0	0
10	1111	09SEP2017	3:08	1	0	0
11	1111	09SEP2017	3:18	1	0	0