PROC SYSLIN performs OLS regression if you do not specify a method of estimation in the PROC SYSLIN statement. OLS does not use instruments, so the ENDOGENOUS and INSTRUMENTS statements can be omitted ...

K-class estimation is a class of estimation methods that include the 2SLS, OLS, LIML, and MELO methods as special cases. A K-value less than 1 is recommended but not required. MELO is a Bayesian ...