=
4
PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28
[f the intervals between 0 and 1 and between 1 and 2 are the
same, then ® =1.
The effect of this method of projection will be to change
each coefficient in the way that it has been changing in the
past. This can be only approximately correct, and so it is of
particular importance to get as much direct information from
outside as possible. For example, in Britain between 1954 and
1960 the oil component of the input of fuel into electricity ge-
neration rose from a very small figure to nearly 20%. A con-
linuation of this trend would make oil the dominant fuel input
by 1970. But we know that this particular trend will not
continue as in the past because of the kind of fuel used in
generators that have been built very recently and are planned
for the immediate future. The direct information can come
either from current statistics of input-output coefficients which
are available in a limited number of cases, for example coal
used in coke ovens, or from outside knowledge, as in the case
of oil used in the generation of electricity.
We have used such direct information wherever possible
and then applied (IV. 58) to the remaining elements of the
input-output matrix. We have then discussed the results of
this exercise cell by cell and changed the projections subjectiv-
ely if this seemed desirable. The results of such a survey are
illuminating. For example, we were surprised to find that in
our projections the coefficient for machine parts and repairs
into agriculture rose, indicating a greater use of machinery,
while the coefficient for petroleum products fell. We were told
that this was not really surprising because of the substitution
of the less processed and cheaper diesel oil for petrol and that
our results were a reflection of this particular type of fuel
economy. We therefore did not change our provisional result
in this case, although we did in manv others.
d) Output levels. If we bring together the foregoing cal-
culations, we can estimate output levels in 1970. In the preli-
11 Stone - pag. 70