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*** Schaeffer Model (Lobster data)  -  EXST7025 Example   ***;
*** Data approximated from graph digitization             ***;   
*** Source: Fogarty, M. J., Time series models of the     ***;
*** Maine lobster fishery: The effect of temperature.     ***;
*** Can. J. Fish. Aquat. Sci. 45:1145-1153                ***;
*** Year Catch Effort Temperature                         ***;
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OPTIONS NOCENTER PS=61 LS=78 nodate nonumber;
FILENAME INPUT 'C:\Geaghan\Current\EXST7025\Spring2008\SAS\Shaefer\lobster.dat';

DATA ONE; INFILE INPUT MISSOVER;
   TITLE1 'Analysis of Catch and Effort data for Homarus americanus';
   INPUT YEARP1 CATCHP1 EFFORTP1;  *** input lagged future values = t+1 ***;
  ** Use SAS LAG statement to create values at time t and t-1 ***;
        YEAR   = LAG1(YEARP1);      YR = YEAR - 1927;
        Y = YEAR - INT(YEAR/10)*10;
        CATCH  = LAG1(CATCHP1);     CATCHM1  = LAG2(CATCHP1);
        EFFORT = LAG1(EFFORTP1);    EFFORTM1 = LAG2(EFFORTP1);
        CPUEP1 = CATCHP1/EFFORTP1;  CPUEM1 = CATCHM1/EFFORTM1;
        CPUE   = CATCH / EFFORT;
  ** Calculate various versions of the dependent variable here ***;
   IF CATCH EQ . THEN DELETE;
   DROP YEARP1; RUN;