# The SYSLIN Procedure

### Using PROC SYSLIN

First specify the input data set and estimation method in the PROC SYSLIN statement. If any model uses dependent regressors, and you are using an instrumental variables regression method, declare the dependent regressors with an ENDOGENOUS statement and declare the instruments with an INSTRUMENTS statement. Next, use MODEL statements to specify the structural equations of the system.

The use of different estimation methods is shown by the following examples. These examples use the simulated dataset WORK.IN given below.

data in;
label q = "Quantity"
p = "Price"
s = "Price of Substitutes"
y = "Income"
u = "Unit Cost";
drop i e1 e2;
p = 0; q = 0;
do i = 1 to 60;
y = 1 + .05*i  + .15*rannor(123);
u = 2          + .05*rannor(123) + .05*rannor(123);
s = 4 - .001*(i-10)*(i-110) + .5*rannor(123);
e1 = .15 * rannor(123);
e2 = .15 * rannor(123);
demandx = 1 + .3 * y + .35 * s + e1;
supplyx = -1 - 1 * u + e2 - .4*e1;
q = 1.4/2.15 * demandx + .75/2.15 * supplyx;
p = ( - q + supplyx ) / -1.4;
output;
end;
run;