> It would be trivial to use a different index type which introduces the opposite bias, but they don’t.
What would be an example(s) of this different type of index? Do you know of any (online?) resources that explain these differences about different types?
The Paasche index would be the alternative to the indexes used today that would tend to understate inflation. It is not commonly used however. If you wanted to be move clever you could use the Fisher index or Marshall–Edgeworth index, which would give lower inflation values than the methods commonly used today while also being easier to justify since you can argue that you believe they’re more accurate than other methods.
I did make a mistake in my comment above - I said that we use a Laspereys index, but we actually use a Lowe index, which is modification to the Laspereys formula.
What would be an example(s) of this different type of index? Do you know of any (online?) resources that explain these differences about different types?