[candiodari]

That's not really how substitutions work. Substitutions work by replacing what people used to buy with what people buy now.

Now your criticism remains valid, to a slightly lesser extent, because if everyone gets poorer and trades wool for acrylic socks, they get replaced in the basket. Not to artificially depress inflation, but to reflect what everyone (now poorer) actually buys.

The issue is, obviously you need substitutions. The finance example is going to be horses, so let's go with that. Nobody buys or rents horses anymore. They are exclusively the domain of recreation. So having them in the index would be lunacy.

One measure people use is the "big mac inflation index", a PPP index. That one would tell you that inflation between 2010 to 2020 is about 76%, or indeed 5.8% per year average.

But that's how the FED chairman Powell (and all those before) will dress it up these days.