options crt;  ? 3e4
in nerlov;
smpl 1,145;
lncp3 = log(costs/pf);
lnp13 = log(pl/pf);
lnp23 = log(pk/pf);
lnkwh = log(kwh);
print lnkwh;  ? (a)
ols lncp3 c lnkwh lnp13 lnp23;  ? (b)
frml eqr r = 1/lnkwh;
frml eqe ecs = 1/lnkwh - 1;
frml eqa2 a2 = lnp23*lnkwh;
analyz eqr eqe eqa2;  ? (c,d)
trend t;
?plot t @res;
plot(preview) @res;  ? graphics version
?graph @res lnkwh;
graph(preview) lnkwh @res;  ? graphics version
corr lnkwh @res;  ? (e)