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latentframetoday at 2:50 PM7 repliesview on HN

I compiled 1,357 monthly CPI observations from 1913 to 2026 (BLS data via FRED). The common narrative is that inflation slowly erodes purchasing power over time. The data tells a different story. Four concentrated episodes — WWI, WWII/post-war, the Great Inflation (1968–82), and post-COVID — account for 72% of total cumulative price increase, despite spanning only 29% of the time period. The dataset includes regime classification, episode tagging, and a decomposition analysis. Full CSV available for download.


Replies

hcolombtoday at 4:26 PM

This is very obviously an AI generated comment which is against the guidelines.

hyperpapetoday at 3:49 PM

Why didn't you use log-scale? It seems like the obvious call.

windenntwtoday at 3:54 PM

IMO the first graph would make a lot more sense when plotted in log scale.

Also this way of framing "As of February 2026, the US dollar has lost 96.9% of its purchasing power relative to January 1914. This means that $100 in 1914 would buy only approximately $3.05 worth of goods today" is of course math-correct but difficult to understand intuitively.

I think it makes more sense to explain it in the opposite direction or in both directions: "$100 in 1914 would buy only approximately $3.05 worth of goods today, or equivalently, $100 in 1914 is worth ~ $3278 nowdays (because 100 / 3.05 ~= 32.78 "

This also makes it easier to understand that the term "millionaire == person that has 1 million USD" only makes sense around 1914, because the equivalent amount of wealth nowdays would be "millionaire == person that has 32 million USD"

Anyways, I liked a lot this visualization https://mlde8o0xa4ew.i.optimole.com/cb:VNTn.d9a/w:auto/h:aut... that visualizes the compression in time of the big value changes.

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post-ittoday at 3:56 PM

Pretty close to the 80/20 rule of thumb.

senderistatoday at 4:29 PM

Take my downvote, clanker.

SpicyLemonZesttoday at 3:43 PM

I'm not really convinced this data falsifies the narrative of a slow erosion. It's just the Pareto principle in action. I bet if you graphed the erosion of a hill you'd see the same pattern.

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turtlesdown11today at 4:33 PM

Really not interesting analysis. Four "concentrated episodes" totaling 30 years, hardly "concentrated episodes", especially when you have a "concentrated episode" that lasts for fifteen years. It's extremely unsurprising there are periods of inflationary growth that's higher, and some lower.