SERIES CORRELATED WITH EXPENSES 235
described respecting the percentage deviations given in Table
136, the difference being that in Table 140 the percentage changes
from year to year are taken as the bases of classification. Then,
for each classified group, the net year-to-year changes are determined
 for the associated series.
An inspection of the stub (horizontal) classes of Table 140
shows that the direction of change in ratios of total expense
was upward in go district-years and downward in 32—six yearly
changes being possible between 1919 and 1925 for each of the
twelve districts. If the direction of change alone is first considered,
 it is found that (1) net increases and decreases from year
to year in the ratios in the following series are positively correlated
 with increases and decreases, respectively, in ratios of total
expense to earning assets: loans and discounts, gross earnings,
and net earnings to earning assets; and (2) net year-to-year
changes in the ratios of investments to earning assets, and of
demand deposits to earning assets, are negatively correlated with
similar changes in ratios of total expense to earning assets.
Further study of the table shows that while the net changes
in ratios of time deposits to total deposits and to earning assets
and in ratios of total expense to gross earnings were upward for
both rises and declines in ratios of total expense, the rise was
greater for districts having increasing than for those having decreasing
 ratios of total expense, and that the greater the percentage
 change in ratios of total expense, whether increasing or decreasing,
 the greater the net percentage rise in each of the associated
 series. In general, net percentage amounts of change of
the ratios in each of the various series tend to be positively correlated
 with percentage amounts of change in ratios of total expense
 to earning assets, while the directions of change in some
of them are positively and in others negatively correlated with the
directions of change in total expense ratios. In the latter connection,
 loans and discounts and demand deposits are of interest.
It is of interest to observe also, that positive correlation of
differences from district averages and of year-to-year changes
obtains between ratios of gross earnings and of total expense, and
that negative correlation obtains for district differences and
changes from year to year between ratios of investments and of
total expense.