It's decent only if you believe inflation = CPI

In actuality, the CPI is lower than inflation because technological advancement, automation, and economies of scale (due to globalization etc) are driving consumer prices low. In other words, if factories are still producing things like they were 20 years ago, the CPI would have been much higher, and that higher number is closer to what should have been the inflation number.

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ifwinterco 13 hours ago | parent | next [-]

A better measure is what % of the total money supply you have.

I.e. you started out with 2e-20 % of the total money, and after 5 years you now have 1e-20 % of the total money, then whatever happened to CPI, you've been diluted and you would probably have been better off investing in something else other than cash.

That makes sense in theory, but in reality what "total money supply" is is a complete can of worms and basically impossible to measure

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JumpCrisscross 14 hours ago | parent | prev [-]

> if factories are still producing things like they were 20 years ago, the CPI would have been much higher, and that higher number is closer to what should have been the inflation number

This is an impossible counterfactual to test. In reality, tracking value across time requires adjusting for immeasurable preferences. This is why inflation is really only a useful measure for personal purposes across periods of years. It’s only macro economically interesting across a generation and close to meaningless longer than a human lifespan.

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hnfong 13 hours ago | parent [-]

I think it's so obvious that no testing is needed, but generally I don't disagree with your take.

The thing is one really needs to understand what "real yields" mean when investing in bonds, i.e. it means your purchasing power with respect to cheap commodities tracked by the CPI is preserved, but it doesn't necessarily mean "value" (whatever that means in the abstract) is retained.

	▲	JumpCrisscross 13 hours ago \| parent [-]
		> it means your purchasing power with respect to cheap commodities tracked by the CPI is preserved CPI isn't a measure of commodities. And "CPI" is a bit of shorthand, given there are pretty much as many measures of consumer and producer prices as there are economists. > it doesn't necessarily mean "value" (whatever that means in the abstract) is retained This is what any measure of inflation ultimately seeks to measure. Purchasing power is intrinsically tied to the basket of goods and services its measuring. That basket varies across people and time as preferences vary.