[chanri]

There are many cities in the county of San Diego. The city of San Diego (where you are suggesting that the 200k number came from) is about 10-20% of the size of the county of San Diego.

They should make the size of the bubble smaller to only cover the area of the city like you are saying.

[showerst]

The issue isn't really the city scale then, it's the numbers for the avg house price: http://www.trulia.com/real_estate/San_Diego-California/marke...

http://www.trulia.com/home_prices/California/San_Diego-heat_... breaks it down better, my domain knowledge of SD ends there, I couldn't tell you whether they're showing an accurate pic of what constitutes most people's idea of San Diego.

The circle is definitely scaled correctly though, the ratio of area of the circle to population (1306300 people per 1809 pixels, or about 722 people per pixel) is within the margin of error for my numbers for new york (about 662ppl/pixel), and LA (about 725ppl/pixel).