the meaning of "for"

Question

1.The market basket may not be representative, it can overstate or understate inflation for certain groups.

2.CPI does measure the variation in price for retail goods and other items paid by consumers, it does not include things like savings and investments.

I find it hard to understand the meaning of the preposition for,
when it acts as an adverb, it isn't that difficult,
but when it acts as an adjective , it completely baffles me, like the examples above.

I guess the fors above are adjectival and modifies the preceding noun ,
but how do I understand or interpret the meaning of these fors?

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Author posted in comment:

If it's an adverb:

"I bought this for you"

"for" here tells the purpose or introduce the people receiving the thing.

That's the meaning I know.

Answer 1

"For" can be a preposition or a conjunction. I am not sure what you understand by "adjective" or "adverb".

Now let's analyze your examples, from simple to complicated.

You say that you completely understand "for" in this sentence:

"I bought this for you"

I will "simplify" it to:

bought ... for (you)

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We move to example 1:

1.The market basket may not be representative, it can overstate or understate inflation for certain groups.

I will "simplify" it to:

overstate or understate inflation for certain groups

and further to:

overstate ... for (certain groups)

which is totally similar with:

bought ... for (you)

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Moving to example 2:

2.CPI does measure the variation in price for retail goods and other items paid by consumers, it does not include things like savings and investments.

We simplify it to:

measure the variation in price for retail goods

and further to:

measure ... for (retail goods)

which is again totally similar with:

bought ... for (you)

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So as you can see, it is a matter of "splitting" the sentence properly, not a matter of changing the meaning of "for".

In all examples we have the structure:

verb + ... + for + (something)