How Zillow's Trick or Treat index gets it wrong

zillow index
© Zillow trick or treat index

Last Hallowe'en we looked at how you can Get more candy on Hallowe'en with New Urbanism, and noted the Zillow analysis of the best cities to trick or treat in. The big real estate site crunches house values, crime data, density and population age. "This data combines to give us the safest cities to trick or treat, where trick-or-treaters can get the best candy, in the least amount of time."

This Hallowe’en, Henry Grabar looks more closely at this index in Citylab, and finds it “a hopeless muddle” because it ignores urban design and house form, all issues raised by Brent Toderian in his trick or treat test. Brent has written

In city planning and design, there's an old saying about the "Trick-or-Treat Test." It's often brought up in the context in suburban home design: Can kids easily find the front door to your house, or must they poke behind the huge multi-car garage, past the parking asphalt, to ring your bell?

The Zillow index ignores this. Grabar writes: downgrading the importance of urban design, Zillow winds up with some bad results. And although I know I shouldn’t care about Zillow’s Halloween rankings, I do—if only because the real estate listing company is misunderstanding and obscuring a valuable idea about how we build cities.

Toderian describes the streets that make for good trick-or-treating, and it is likely that they come up high on Zillow, because these are traits of successful residential neighborhoods:

  • Tree-lined streets designed for walkers more than speeding cars.

  • Enough density and community completeness, to activate what I call "the power of nearness" - everything you need, nearby.

  • Good visual surveillance through doors and stoops, windows (and I don't mean windows in garages), porches and "eyes on the street."

  • Connected, legible streets that let you "read" the neighbourhood easily -grids tend to be good for this, but other patterns work too.

You can actually put a number on this; Paul Knight did a few years ago in his landmark planning study, Maximize Your Halloween with New Urbanism

He developed a formula for calculating a Candy Score that took all the urban design variables into account and found that " the quantitative metrics fall in favor of the walkable, mixed-use communities." He notes also that mixed use communities are more likely to have a nearby dentist.

In the end, Brent Toderian's design criteria or Paul Knight's Candy Score formula are a lot more granular and specific, compared to Zillow's go-where-the-rich-people are. You want to go where the people are, and that is in the walkable neighborhoods with narrower frontages for shorter walks between doors. Every kid knows that.

How Zillow's Trick or Treat index gets it wrong
It focuses on dollars instead of density.

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