They're wrong, they got confused because the header column on the data is labeled "age of householder". This is because the data is the ratio of householders who own their homes to total householders, broken down by the age of the householder.

The title of the tables I'm looking at are "Homeownership rates by Age of Householder", which makes it pretty clear what they mean.

https://www.census.gov/housing/hvs/files/qtr423/tab7.xlsx

https://www.census.gov/housing/hvs/data/histtab19.xlsx

If two or more people rent the same "household" (house, apartment, couple of rooms) they are only counted a single time.

1 homeowner and 1 renter = 50%

1 homeowner and 2 renters in the same apartment = 50%

1 homeowner and 200,000 renters in the same apartment = 50%

1 homeowner and 2 renters in 2 different apartments = 33%

It's a ratio of homeowners to the number of buildings the rest of us rent out.

I notice that this isn't even close to the claim GP quotes you making. It's wild to me that you're out here telling the other guy to just own up to their "misunderstanding" while furiously backpedaling your own.

There is subtlety of the "renters are probably systematically undercounted due to the vagaries of householding" variety, but that is neither a straightforward effect (a homeowning married couple with 2 of their parents and 3 adult children under the same roof and 1 single renter in an apartment = 50%!) nor is it remotely what you were saying to begin with.

It's just the number of housing units owned versus rented. The occupancy is ignored in both ownership [even if joinly owned] and rental.

As per the definition: "The householder refers to the person (or one of the persons) in whose name the housing unit is owned or rented"

"Homeownership" rate is a bit of a misnomer, since it's the proportion of occupied housing units which are occupied by their owners.

Homeownership by age of householder restricts the reference set of housing units to those which are occupied by a householder in the specified age group.

The distinction is between renting and being a leaseholder I think.

I live with roommates and I'm not on the lease here, so IIUC I would be considered neither a homeowner or a renter for these purposes.

living with parents, or someone else.

or else a bunch of roommates, some of whom may not be on the lease.