While we're on this subject - does anyone know how median household income is actually calculated within the USA? I feel like there's some weird distortion bubb

While we're on this subject - does anyone know how median household income is actually calculated within the USA? I feel like there's some weird distortion bubble within the bay area because I've seen the data on household income within the bay area and the amount of households under $100k/yr seems way too low. Individuals under $100k/yr would make sense but households? No - it doesn't add up. For instance, the median household income in SF is around $100k/yr. By its own measure in SF - $100k/yr is considered poor for a household of 4. I have a hard time believing that somewhere around 50% of residents in SF are poor. I feel like something is off with the way this is measured. How can it be that a large amount of housing is SFH (can't be rented on a $100k/yr income), about half of people rent here (thus - half of people can't be prop 13 beneficiaries), and yet the median income is $100k/yr? The median rent in SF is beyond $2,500/month - which is the max a $100k/yr household can afford. I've looked at the stats a bit and it just feels like the incomes are estimated to be too low across the board for households. I see way too many homes/apartments where there are 3+ working adults. If I look at all the people I've worked with or socialized with - I can't find a single one where the household income was below $150k+. I know there's a bubble in terms of what I've worked with or interacted with - but the truth is that anyone below $100k/yr income was very likely renting with someone else. (Which would push the household income higher)