Dear Art, You are absolutely correct! I use another date (as this dataset is a bit confusion) the dead_date do not reflect for death and I am asked to use fu_time. And the code work fine. I much appreciate and thank you very much, Art, and thanks everyone's times for discussion. Phan S. ... View more

Dear Art, good morning! Pls. kindly see the date SAS. I will fu with you late today, I hope to show the issue to my colleague. Thanks. Phan                                                    DEATH_                        Obs     ID FARVDT              DATE                         16     310 01MAR2010            .                         17     340 28APR2008            .                         18     350 22NOV2006    27MAR2008                         19     360 23FEB2004            .                         20     370 07OCT2009            . ... View more

Dear Art, Please kindly see the log. I will see a stat person tomorrow morning and will fu you. 8617  /*person-year*/ 8618  py_dead1=yrdif(farvdt, death_date, 'act/act'); 8619  py_dead2=datdif(farvdt, death_date, 'act/act'); 8620 8621 8626  run; NOTE: Invalid argument to function YRDIF at line 8618 column 10. NOTE: Invalid argument to function DATDIF at line 8619 column 10. Thanks, Phan ... View more

Dear Art, Thanks for the follow-up. Indeed, I am working on 9.3. In fact, this message from log file: character values have been converted  to numeric values at the places given by ... referred for another (I'm sorry to confuse you). Lately, I will send you a log file that may help you to understand the issue when I ran the code. I am in Vancouver, a bit inconvenience at my workplace for Internet. Phan ... View more

Dear Everyone, My sincere apology that I couldn't get back last night. To Art, I tested the yrdif (as well as dtdif) using methods/instructions from SAS Helps, unfortunately I had a message from log file: character values have been converted  to numeric values at the places given by ... I am not sure what is wrong with the code. Greatly, I used the approximate formula (doc@duke), it appears to be fine for my results. As Reeze's comment, however, I need to develop several step fro proc summary, proc freq and proc mean to calculate 'sum' of variable that I need. Overall, I think to calculate person-year is required several steps. These steps are very helpful for new SAS users like me. One thing that I have no idea for Art is the code does not work. If possible, I will see a stat person in my place if he can help me to identify the erros. At the meantime, I much appreciate and want to thank everyone in helping me this procedure. Again thanks. Phan S. . ... View more

Dear Art, Many thanks for your follow-up. Through Reeze's comments, it appears that you are logic. I may not have time to run a test at this moment, but will do tonight. I am happy to inform you. Thanks, Phan ... View more

Dear Reeza, My sincere apologies as I have difficulties with names. I appreciate and thank for your telling me. Re. your advice, I will test later tonight and will follow-up. Phan ... View more

Hello, Thanks for your contribution. I will follow-up later. Thanks Phan ... View more

Dear Art, I am not sure the 'calculation person-age' is similar to 'person-year' that Reeza has mentioned. He provides a useful document about the concept of 'person-year'. I am trying to build SAS codes and I would like to share if I achieved. Thanks, Phan ... View more

Hello, I do have the Eric document. I helps to understand the concept of person-year. I do agree with you that I have to write code my myself. At the meantime, I don't think I have never seen an example or taught about SAS syntax to apply for person-time. It would be very helpful if any SAS experts can built an example for this issue for SAS users. Thanks. Phan ... View more

Hello, I will use log10 as well as actual values. I do not use percentage. Re. cumulative changes, I will look for each subject as well as for the cohort. Thanks, Phan S. ... View more