CONFERENCE BOARD INDEX 29 
base period of the Board’s series is, therefore, somewhat 
broader than is apparent on the surface. 
With July, 1914 as the base period, a number was com- 
puted in June and November, 1918, and in March, July and 
November, 1919. In 1920 and in the years following, num- 
bers have been constructed each month. This series, together 
with interpolations for July, 1915, July, 1916 and July, 1917, 
for which dates little exact information is available, constitute 
a continuing measure of changes in the cost of maintaining 
substantially the pre-war standard of living! for families of 
small and moderate means. It is based on retail prices of 
goods and services representative of a complete family 
budget, combined in such a way as to give proper weight to 
each item in proportion to the expenditures therefor by 
wage earners’ families before the war. Until December, 
1925, the figures collected for months other than March, 
July and November of each year were on a somewhat more 
limited basis, as regards both localities covered and number 
of reports, than were those for the above mentioned dates. 
The December, 1925 figures are on the same basis as those 
for March, July and November, and it is now planned that 
in the future the index numbers for all twelve months will 
be strictly comparable. In the present volume the more com- 
prehensive figures will, however, be discussed separately from 
the others. 
. The series based on the more comprehensive surveys is 
given in Table 1 for all dates for which numbers are available. 
Chart 1 shows the same results in graphic form. The method 
of collecting and combining prices of the articles entering 
Into the major items food, shelter, clothing, fuel and light 
and sundries, and of the major items themselves to obtain 
the change in the total cost of living, is described in the pages 
which follow. The detailed results are presented and ana- 
lyzed in Chapter VI. 
. At the time of the Board’s first estimate of the increase 
in the cost of living, great speed was necessary and there 
were no models to follow, either as to basic standards or 
methods of collecting and working out the data. For a 
' It is recognized, of course, that customs and goods available for consumption 
thange, but so far as possible every contingency here is protected.