With a 5% rent increase, Seattle’s homeless population could grow by 258

It seems intuitive: As rent goes up, more people are likely to find themselves without a home. A study by Zillow released last week attempts to put concrete numbers on that. If median rent were to go up, how many people in the Seattle metropolitan area would become homeless as a result?

Working with University of Washington postdoctoral researcher Christopher Glynn, economists at Zillow put together a model estimating how many additional people would experience homelessness with a 5 percent rent increase.

In Seattle, they found the homeless population would likely increase by about 258. By their data, 12,240 people were experiencing homelessness in the Seattle metro, which includes Tacoma and Everett, in 2016.

”We’ve seen so much pressure in rental housing markets that it’s created a rental affordability crisis that has spilled over into a homelessness crisis at lower income levels,” said Zillow senior economist Dr. Skylar Olsen in a statement.

We asked how they arrived at the 258 number. Is it based on rent burden? Is it proportional to previous rent increases compared to one-night counts?

Turns out, it’s a little of all of the above.

“How this technique works is to first built a basic model of how important variables relate to each other,” Olsen told Curbed Seattle. “For instance, how does population growth impact the total number of homeless people?”

One-night counts, Skylar said, aren’t necessarily the most accurate—not because of methodology or because they aren’t valuable, but because of the challenge involved in counting those experiencing homelessness individually. So researchers asked themselves how to integrate those numbers into their study, and then how do rent changes increase homelessness?

“Once we have the structure of the model mapped out,” continued Olsen, “we pass census population numbers, one-night homelessness counts, and our own rental data through the model so that the estimates we report best reflect the patterns in the data that we observed over time and the logic of those relationships.”

Their numbers, Olsen said, hold even assuming that one-night counts become more accurate over time—especially relevant in Seattle, with a change in methodology between 2017 and 2016—“though under that assumption the difference between counted and estimated total decreases.”

It’s hard to say how Seattle compares to other cities in how our homelessness crisis and affordable housing crisis interact, with different levels of density and different challenges. But Zillow does note in their press release that not all cities have the same correlation between rent increases and the number of people experiencing homelessness, “indicating that they have found a way to interrupt the trend.”