I believe it is skewed since many people in these neighborhoods aren't making their money through salary income (anymore), but instead through interest / dividends.

If you sold your company, aren't working at FB/goog/etc and are sitting on a ton of stock holdings, your income is going to show as near $0

that should be accounted for in govt household income calculations, but I could be wrong. For example, ton of stock holdings will pay you dividends or capital gains.

What you put on your tax return every year doesn't really reflect your actual wealth. Even in tech most people top out at ~$200k-$250k base salaries but you may vest and accumulate millions in stock RSUs that you don't sell in a given year.

Stock RSU vests go on your tax returns.

Ah ok - I'm thinking private shares

Those do too. The only thing that doesn't is deferred compensation in the form of an ISO or NSO. The latter is recognized as ordinary income when exercised.

My working explanation is that it's actually survey data. the richest people either don't answer the survey or understate their actual holdings when they do answer.

Don't RSUs show up on the W-2 as income though (even if you don't sell them)?

They do; RSU vesting is a taxable event. It's counted as ordinary income based on the fair market value at the time it vests and taxes are due immediately. Companies tend to withhold a percentage of the shares and sell them to cover your tax burden.

No, this seems right. The typical distribution of income across the pop., even in a distorted environment like the valley, looks far more like a Poisson distribution with a long tail than a typical Gaussian

137 is a median. Half the people in Palo Alto make less than 137 in household income? Maybe, if you count East Palo Alto. But Atherton at 443 ( https://www.bloomberg.com/graphics/2018-hundred-richest-plac... ) ? seems too low

You don't want to rely on it for means because the high incomes are capped at a relatively low level so that they don't out high-earners in sparse areas. But that shouldn't affect medians.

I can't find the $400k/year number anywhere. The census puts it at "$250,001" which seems like a fishy number.