Sorry for the mess but here is what you mentioned would be helpful. Thanks for the help. 1. Version 9.2 2. Below is my code. I have unbalanced data sorted by company id (gvkey) and year (fiscal year) proc sort data=final; by gvkey year;run; Proc Panel data=final; by gvkey year; model tDm=zcollateral_lag zlog_assets_lag div_pay_lag zmk_book_ratio_lag zmed_debt_industry_lag disclose_lag zoper_income_lag constrain_lag zconserve_lag nol_lag zadvert_lag zfor_income_lag big4_lag zintang_lag dummy06-dummy09 Durable nondurable Energy Manufact Chemical Health Retail BusEquip Telephone/fixeone; run; 3. Here is a copy of the log showing the error. NOTE: There were 6910 observations read from the data set WORK.FINAL. NOTE: The data set WORK.FINAL has 6910 observations and 475 variables. NOTE: PROCEDURE SORT used (Total process time): real time 0.10 seconds cpu time 0.09 seconds 1109 1110 Proc Panel data=final; NOTE: PROCEDURE PANEL used (Total process time): real time 0.07 seconds cpu time 0.01 seconds ERROR: Variable number 0 is not on file WORK.FINAL. NOTE: The SAS System stopped processing this step because of errors. 1111 by gvkey fyear; 1112 model ztDm=zcollateral_lag zlog_assets_lag div_pay_lag zmk_book_ratio_lag 1113 zmed_debt_industry_lag disclose_lag zoper_income_lag constrain_lag zconserve_lag nol_lag 1113! zadvert_lag zfor_income_lag 4. The content variables are as follows: 1 GVKEY Char 6 $6. $6. Global Company Key 13 FYEAR Num 8 F6. 6. Data Year - Fiscal 241 constrain_lag Num 8 202 div_pay_lag Num 8 207 disclose_lag Num 8 212 nol_lag Num 8 464 zadvert Num 8 428 zcollateral Num 8 400 zconserve Num 8 460 zfor_income Num 8 408 zlog_assets_lag Num 8 457 zmed_debt_industry_ Num 8 lag 433 zmk_book_ratio_lag Num 8 425 zoper_income_lag Num 8 413 zresearch_lag Num 8 397 zroa_lag Num 8 421 zsale_lag Num 8 417 zsga_lag Num 8 411 zlog_assets_lag3 Num 8 457 zmed_debt_industry_ Num 8 lag 433 zmk_book_ratio_lag Num 8
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