The city highlighted in black is the reference city.
Blue circles indicate cities where people are looking for housing in the reference city (i.e. they are maybe thinking of moving into the reference city)
Red circles indicate cities where people in the reference city are looking for housing (i.e. they are maybe thinking of moving away from the reference city to the cities with red circles)
So for San Francisco, it is not surprising that many people are looking to move out of the city into nearby cities (like Oakland) and vice versa. The same is true for New York.
More interestingly, a number of people in Chicago, Houston and DC are looking for housing in San Francisco, but few people in San Francisco are looking for housing in those cities.
One weakness of the graphic is that it makes it difficult to tell the net effect of inbound and outbound housing searches. Ideally, there would be a third option next to "Inbound Searches" and "Outbound Searches," that showed a net effect for each city using both red and blue circles.
Also, different reference cities are not comparable using the graphic. For instance, selecting SF as the reference city shows moderate inbound and outbound searches from NYC. But select NYC as the reference city and you'll see that SF doesn't make the top 10 cities for outbound or inbound searches and therefore isn't even shown. As a result, you can tell that there are more searches from NY to LA than to SF, but it is difficult to tell how great that difference is.
Thanks for taking the time to explain the visualization (I didn't build this, but helped with some of the bugfixes). We're super interested in looking at this kind of data, and it's not quite the easiest to explain. There are a lot of small cases that would disappear if we were only looking at the net inbound/outbound, but adding it as a third mode is a good idea.
The city highlighted in black is the reference city.
Blue circles indicate cities where people are looking for housing in the reference city (i.e. they are maybe thinking of moving into the reference city)
Red circles indicate cities where people in the reference city are looking for housing (i.e. they are maybe thinking of moving away from the reference city to the cities with red circles)
So for San Francisco, it is not surprising that many people are looking to move out of the city into nearby cities (like Oakland) and vice versa. The same is true for New York.
More interestingly, a number of people in Chicago, Houston and DC are looking for housing in San Francisco, but few people in San Francisco are looking for housing in those cities.
One weakness of the graphic is that it makes it difficult to tell the net effect of inbound and outbound housing searches. Ideally, there would be a third option next to "Inbound Searches" and "Outbound Searches," that showed a net effect for each city using both red and blue circles.
Also, different reference cities are not comparable using the graphic. For instance, selecting SF as the reference city shows moderate inbound and outbound searches from NYC. But select NYC as the reference city and you'll see that SF doesn't make the top 10 cities for outbound or inbound searches and therefore isn't even shown. As a result, you can tell that there are more searches from NY to LA than to SF, but it is difficult to tell how great that difference is.