Subject: Re: The Berkshire Problem
CPI in recent 6 months (December 2022 to June 2023) is actually only 0.2%
...As I said further along, 6-month inflation (not annualized) was 1.7%,

You're right that my figure was misleading, though the correct figure certainly isn't 0.2%, nor 1.7%.

As with Berkshire's book value, my habit is to use my "point in time" data set, being the figure that was known on a given day, not the figure which was named after a given day.
A quirk of the BLS release date schedule meant the figure I quoted was for the rise during seven data releases rather than six.

The most recent data release now is the "July" figure, released and known as of August 10, CUR0000SA0=305.691
Six months earlier on Feb 10, the most recently known and released figure was still the "December" figure, CUR0000SA0=296.797, as the "January" figure was not released till Feb 14.

So, comparing the "last known number" to "last known number six months earlier", the rise between the two is the 3.0% that I quoted.
The underlying data collection dates were, however, seven months apart, which I didn't notice, sorry.

Had it been only a couple of days earlier or later, the "most recently known and released" figures would have been for underlying data collection months six months apart.
Had I posted a couple of days earlier I'd have said 2.80% (the rise from the release named "December" till the release named "June"),
and a couple of days from now I'd have said 2.18% (the rise from the release named "January" till the release named "July").
Right on the release date cusp I guess the most "correct" figure would be the average of those two, around 2.50%.

It's always surprised me that they make it so extremely difficult to find the actual CPI. They quote the year-on-year rise everywhere, but the actual index level is hard to find.
This is the link https://download.bls.gov/pub/t...
For the usual all-urban figure you have to search for CUUR0000SA0 and remember that M13 means the average for a calendar year, not a real month.
That's the "All items in U.S. city average, all urban consumers, not seasonally adjusted"
Seasonal adjustment isn't appropriate in this context, especially not this year with its wild swings due to things other than the time of year.

(reminder that all rates being discussed are six-month rise not annualized rates)

Jim