[dragonwriter]

> Yes, and this confirms one suspicion of them I had, that they only work in one direction. They ever adjust inflation upward when products get worse:

Well, it asserts that but doesn’t provide a basis for the claim, which directly contradicts BLS: “The hedonic quality adjustment method removes any price differential attributed to a change in quality by adding or subtracting the estimated value of that change from the price of the old item.” [0]

Given that the author focus almost the entirety of his piece on hedonic adjustments discussing new car price data as illustration without ever mentioning that this is a CPI component to which the hedonic quality adjustment method is not applied, I would trust its unsourced claims not at all, and be extra sure to double check any sourced claims.

[0] https://www.bls.gov/cpi/quality-adjustment/