This
is an update of our previous post with an addition of two more months and
calculation of the slope of the new trend.
We
found sustainable linear trends in the difference between the headline and core
CPI in 2007. We also were the first to suggest
that the linear trend between 2002 and 2008 to be reversed to the opposite
after an extended period of strong fluctuations. These findings are currently
validated by six years of observations – the studied difference is on a
sustainable linear trend since the middle of 2011. When extended into the
second part of the 2010s, this trend implies that the joint consumer price of
food and energy will be falling against other consumer goods and services in
the headline CPI. (Figure 4 is an update,
which demonstrates the slope of the new linear trend is similar to that between
1987 and 1999.)
We
have been routinely reporting on the difference between the headline and core
CPI since
2008. Figure 1 illustrates our general finding that this deference can be
well approximated be a set of linear trends. The last trend likely finished in
2009. That’s why we expected a new trend to evolve since 2011 into the late
2010s.
The
U.S. Bureau of Labor Statistics has reported the estimates of various consumer
price indices for December 2013. Figure 2 shows the predicted trend and the
actual difference since 2002. The studied difference has been fluctuating
around the zero line between in 2009 and 2011 and then showed a turn to the early
predicted trend (Figure 3). Essentially,
the zero difference suggests that the core and headline CPI are practically
equal and evolve at the same monthly rate, i.e. the joint price index of energy
and food has been following the price index of all other good and services (the
core CPI) one-to-one. Figure 4 shows
that the new trend has finally stabilized and the observed difference between
the core and headline CPI (normalized to the headline CPI) demonstrates no large
deviations from this trend. The slope of 0.0021 per year is similar to that
observed between 1987 and 1999. This is a good indicator that the next 10 years
the difference will follow the current trend, i.e. the core CPI will grow at a
lower rate that the other CPI components.
Figure 1. Two trends in the difference between the headline
and core CPI.
Figure 2. The evolution of the difference between the core
and headline CPI since 2002.
Figure 4. The new trend is similar
to that between 1987 and 1999. The duration of the new trend will likely be
similar, i.e. 12 years
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