Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

Since the census data did not include freight rates, it was neces-
sary to use our other data sources for the rate equations. This
. necessitated conversion of those data from their.original AAR groupings
into the STCC groups. 13 Freight rates were then regressed on distance,
quantity, density and price, as before. These estimates are presented
in Tables 4.35 through 4.38 following this section. Table 4.36 also
contains the estimated coefficients for water transport of STCC group
29. As these rate results are quite comparable with those presented
previously by AAR group, we shall concentrate on the demand equations.
Substituting equations (4.46) and (4.47) into (4.43), (4.44) and
(4.45), 'we obtain
(4.48) Q
r
+ Qa - OT c
a + yA
%
(4.49) -b 0 + T c
r -r
(a + f ) + (C
r r + g )
r
M
r
(4.50) -b Q + T c -(am f) + (c + g ) M.
m m m m m
11. See footnote 8.
12. An investigation was made of the possibility of aggregating published
freight tariffs to obtain rates for the selected commodity groups.
It was found that due to the large number of commodities contained in
each STCC group and the many , possible rates for each commodity, from a
single city to another city, because of quantity discounts, packaging
specifications, etc., a very expensive effort would be required to produce
any reasonable results.
13. This was a very subjective procedure.as the codes were largely
incompatible. An attempt was made to match each classification to the
other, individually. The following groupings appeared to contain a.
minimum of misclassification.
STCC 26 -- MR 653, 657, 659, 661, 663, 665, 669 and 671
STCC 29 -- MR 501, 503, 505 and 507
. STCC 30 -- MR 525 and 549
STCC 32 -- MR 663, 637, 639, 641, 693, 695, 701 and 721.
127