would be used as the price for July, August, September, and October, or
until the new season begins. This method would be of little value when
applied to a single crop; but when a number of crops are so treated, the
effect is largely offset by the varying marketing periods of the different
short-season crops. The seasons do not open and close simultaneously;
they are not of equal length; and, as some seasons are closing, others
are opening. The effect of this method on the combined index is greatest
in July, August, and September. Most other months have a fairly adequate
representation of actual prices from sales.
 The inclusion of closing (or last available) prices affects the citrus
and vegetable group indexes most. It may give them a slight deviation from
an index calculated by using average prices only in months reported, or
months of sale. The method used gets away from the problem of a constantly
changing base as crops move into and out of season.
 Price relatives are calculated only in months of sale for all products.
Base prices for individual commodities also represent an arthmetic average
of prices reported in the base period.