options crt;  ? 6e8
in kopcke;
freq q;
dot e s;
smpl 56:1,86:4;
olsq i. c y-y(-6) k.lag;
rename @res res1;
ar1 i. c y-y(-6) k.lag;  ? (a)
?
?  instruments for Y -- correlated with Y but not with residual
?  (i.e. i(-1) ) -- u and u(-1): capacity utilization.
?
list ivs c u u(-1) y(-1)-y(-6) k.lag;
corr y res1 ivs;
2sls(inst=ivs) i. c y-y(-6) k.lag;  ? (b)
?
ar1(inst=ivs,fair) i. c y-y(-6) k.lag;  ? (c)
enddot;
?
?  same thing using PDL
?
set m=10;  ? PDL lag length for equipment
dot e s;
smpl 56:1,86:4;
olsq i. c y(4,m,none) k.lag;
ar1 i. c y(4,m,none) k.lag;  ? (a)
2sls(inst=ivs) i. c y(4,m,none) k.lag;  ? (b)
ar1(inst=ivs,fair) i. c y(4,m,none) k.lag;  ? (c)
?
set m=12;  ? PDL lag length for structures
enddot;