** 13-Dec-2021 World View: Interest rates and the Law of Reversion of the Mean
richard5za wrote: Mon Dec 13, 2021 3:06 am
> without any corrective action we will just watch inflation come
> down? Never seen that before
richard5za wrote: Mon Dec 13, 2021 4:16 am
> Yes, but just looking at an historical inflation table doesn't
> tell you very much. The interest rates in these years were "up a
> bit" versus the previous year, but other factors would include
> currency exchange rate, trading partner inflation figures, oil
> price, gdp growth, political objectives, etc, etc. Complicated
> stuff where mechanical projections don't work at all well.
If I understand you, you're saying that some or all of these factors
that you've listed were the "corrective action" that brought about the
cpi decreases in 2009 and 2015. I'd be curious to know which of them,
specifically, provided the "corrective action" that you're saying was
necessary. And don't some of these factors also apply today?
There are probably hundreds of such factors. If you watch CNBC and
Bloomberg TV and Fox Business Network, as I do, then each analyst
guest seems to have a different factor or list of factors. "Yes, my
friends, more people are getting pizza for lunch, which is increasing
demand for Wesson oil which is being hit by supply chain issues, and
that alone is the greatest factor increasing the cpi."
Let's look at it a different way. Let's ignore the myriad factors,
and just look at the cpi as a variable by itself:
- In Jan 1921, the cpi was 19.0
- In Jan 2021, the cpi was 261.582
So that's a 100 year period. Let's compute the average annual change
in the cpi during this 100 year period.
So if x is the annual change in the cpi, then we have this equation:
19.0*(1+x)**100 = 261.582
Solving gives you x=0.02622 or 2.26%.
We now apply the Law of Reversion of the Mean. If the inflation rate
is below 2.26% for a while, then the Law of Reversion of the Mean says
that it will have to be above 2.26% for by an equivalent amount by a
roughly equivalent period of time. And vice-versa.
So the annual inflation rate has been well above 2.26% since March
2021. But it was well below 2.26% since Sept 2018 before that. This
suggests that the current high rates are a reversion from the earlier
low rates. But this can't go on forever, and I think that most people
believe that the current interest rate surge will end in the new year.
So I'm suggesting that the end may come as early as February, thanks
to the "corrective action" provided by such factors as supply chain
problems clearing up, holiday-based demand decreasing, and
post-holiday sales bringing retail prices down. It may start coming
down a bit later than that, but the Law of Reversion of the Mean says
that it won't be much later. And that doesn't mean that the cpi will
fall below 2.26% in February. It means that the cpi will have peaked
in February, and will start falling month after month, until it's
below 2.26% and, indeed, until it's below 0.