Let me start by asking a clarifying question. In the dataset, the 'cpi' variable is described as a consumer price index with no further qualification. In the documentation, I couldn't find any more information about it, in general or in the specific case of the US.

In the main article (section II.C. Calculating returns), the formula being used to derive real returns from nominal returns appears to imply that the CPI index for a given year is the index value at the

end of the year. Applying the same formula to the nominal returns (e.g. eq_rt) from the dataset did result in real returns that match the main article (e.g. I checked the arithmetic average of such real returns for a few countries, this matches the article).

On the other hand, I cannot make sense of the actual CPI values (more precisely the annual rates derived from such values) when comparing to the US Bureau of Labor Statistics (BLS) numbers we have in the

Simba spreadsheet (which come straight from BLS, computing Dec to Dec).

Could the MacroHistory authors clarify the exact semantics of the 'cpi' variable and also explain where the corresponding numbers are coming from for the US?