https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728114#M226567 Why not the third obs take flag=1 ? since the gap is only two days . Mon, 22 Mar 2021 11:18:49 GMT Ksharp 2021-03-22T11:18:49Z https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728112#M226566 <P>Hello,</P><P>I have a dataset like this :</P><TABLE><TBODY><TR><TD>ID</TD><TD>date</TD><TD>days</TD></TR><TR><TD>ID1</TD><TD>02/03/2017</TD><TD>28</TD></TR><TR><TD>ID1</TD><TD>30/03/2017</TD><TD>30</TD></TR><TR><TD>ID1</TD><TD>01/05/2017</TD><TD>7</TD></TR><TR><TD>ID1</TD><TD>10/05/2017</TD><TD>90</TD></TR><TR><TD>ID2</TD><TD>24/12/2018</TD><TD>14</TD></TR><TR><TD>ID2</TD><TD>09/01/2019</TD><TD>56</TD></TR><TR><TD>ID2</TD><TD>06/03/2019</TD><TD>20</TD></TR></TBODY></TABLE><P>I want to add a flag which will take 1 if there is 3 consecutive months (90 days) by ID -a gap of 1 or 2 days is allowed- otherwise will take 0 :</P><P>&nbsp;</P><TABLE><TBODY><TR><TD>ID</TD><TD>date</TD><TD>days</TD><TD>end_date</TD><TD>flag</TD></TR><TR><TD>ID1</TD><TD>02/03/2017</TD><TD>28</TD><TD>30/03/2017</TD><TD>0</TD></TR><TR><TD>ID1</TD><TD>30/03/2017</TD><TD>30</TD><TD>29/04/2017</TD><TD>0</TD></TR><TR><TD>ID1</TD><TD>01/05/2017</TD><TD>7</TD><TD>08/05/2017</TD><TD>0</TD></TR><TR><TD>ID1</TD><TD>10/05/2017</TD><TD>90</TD><TD>08/08/2017</TD><TD>1</TD></TR><TR><TD>ID2</TD><TD>24/12/2018</TD><TD>14</TD><TD>07/01/2019</TD><TD>1</TD></TR><TR><TD>ID2</TD><TD>09/01/2019</TD><TD>56</TD><TD>06/03/2019</TD><TD>1</TD></TR><TR><TD>ID2</TD><TD>06/03/2019</TD><TD>20</TD><TD>26/03/2019</TD><TD>1</TD></TR></TBODY></TABLE><P>&nbsp;</P> Mon, 22 Mar 2021 11:12:49 GMT https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728112#M226566 SAS03 2021-03-22T11:12:49Z https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728114#M226567 Why not the third obs take flag=1 ? since the gap is only two days . Mon, 22 Mar 2021 11:18:49 GMT https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728114#M226567 Ksharp 2021-03-22T11:18:49Z https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728115#M226568 The sum days of the 3 first rows is 65days &lt; 90 days, that's why the third row will have 0 and not 1 Mon, 22 Mar 2021 11:26:44 GMT https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728115#M226568 SAS03 2021-03-22T11:26:44Z https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728116#M226569 Then the second obs ? since the gap is only two days . 29/04/2017 --&gt; 01/05/2017 Mon, 22 Mar 2021 11:41:12 GMT https://communities.sas.com/t5/SAS-Programming/Flag-rows-with-3-consecutive-months-1-or-2-days-of-gap-is/m-p/728116#M226569 Ksharp 2021-03-22T11:41:12Z