movement, the seasonal factor
between two types of movement; one that exhibits
quasi random fluctuations
and the other where changes appear in the
The size of the first
movement can be measured from the average absolute year-to-year
change in the seasonal factors,
the simple arithmetic mean of
the changes gives an indication
of the size of systematic
movement. Random fluctuations
are measured by statistics
M9 and M11 describe
the size of linear movement.
M8 and M9 are calculated
the data-in Table DI0.
Since users are mostly
in the quality
in the recent years,
MiO and MIl were intro-
duced to describe
the seasonal movement at the end of the series.
to know if
there is significant
movement in the seasonal factors
of the last years because the
then be considerably
the end-weights of the seasonal filters.
is this same distortion
the use of the last
measure the amount of seasonal movement.
the changes of
the three years before
three years are examined in the hope
the seasonal movement remains unaltered
in the end years.
Obviously an average absolute change of .5 in multiplicative
from 98.0 to 102.0 within a year does not
have the same significance
as an average change of .5 coming from
in the range -165 to +200. Therefore,
in Table D10 before proceed-
ing to calculate
Thus the measures M8 to MIl were
When MIl exceeds
recent years are highly distorted
due to the flattening