4 ms·

Seems spurious. Could be talented people move to cities with high earning potential—which happen to be walkable. Do the authors control for that?

rory096 7y ago
It's longitudinal tax data. >We 1st identified the relationship between walkability and upward mobility using tax data from approximately 10 million Americans born between 1980 and 1982.
- pacbard 7y ago
  The data structure doesn’t help with causal inference. Reading the abstract, it looks like the authors are trying to make a causal argument: people are more likely to improve their economic standing because they moved to a walkable city. OP pointed out that this could be due to self-selection of people with the potential of upward mobility to walkable cities. This would lead to spurious correlation between economic mobility and walkability. That is, a third variable (a potential candidate, awareness of climate change) could explain both upward mobility (usually, climate change awareness correlates with education level) and economic mobility (education correlates with higher wages).
tomatotomato37 7y ago
Yeah, something about this study just feels like it will ultimately end up as an example in an article covering the replication crisis or something.
pmart123 7y ago
Without reading the study, this would be my first assumption.
mwfunk 7y ago
Agreed. The most desirable and expensive neighborhoods tend to be the most walkable ones. It would make sense that the people who live in those neighborhoods tend to be more financially successful. It's as if a study came out that showed that, according to their exhaustive statistical analysis, people that drove Mercedes tended to be wealthier than people who drove Chevys. Then they concluded that the key to upward mobility must be to get a Mercedes.
- iguy 7y ago
  It's supposed to be mobility, and I think tracking individuals through their tax returns. (This magic data which only Chetty & co have access to.) So I don't think the Mercedes example works. But I agree that it's very unlikely to be that being able to walk places makes you succeed. Could even be something as simple as enough people owning a few flats in their neighbourhood, which suddenly became super-valuable when lots of google employees showed up. That would look a lot like income mobility.

rory096 7y ago

It's longitudinal tax data. >We 1st identified the relationship between walkability and upward mobility using tax data from approximately 10 million Americans born between 1980 and 1982.

pacbard 7y ago
The data structure doesn’t help with causal inference. Reading the abstract, it looks like the authors are trying to make a causal argument: people are more likely to improve their economic standing because they moved to a walkable city. OP pointed out that this could be due to self-selection of people with the potential of upward mobility to walkable cities. This would lead to spurious correlation between economic mobility and walkability. That is, a third variable (a potential candidate, awareness of climate change) could explain both upward mobility (usually, climate change awareness correlates with education level) and economic mobility (education correlates with higher wages).

tomatotomato37 7y ago

Yeah, something about this study just feels like it will ultimately end up as an example in an article covering the replication crisis or something.

pmart123 7y ago

Without reading the study, this would be my first assumption.

mwfunk 7y ago

Agreed. The most desirable and expensive neighborhoods tend to be the most walkable ones. It would make sense that the people who live in those neighborhoods tend to be more financially successful. It's as if a study came out that showed that, according to their exhaustive statistical analysis, people that drove Mercedes tended to be wealthier than people who drove Chevys. Then they concluded that the key to upward mobility must be to get a Mercedes.

iguy 7y ago
It's supposed to be mobility, and I think tracking individuals through their tax returns. (This magic data which only Chetty & co have access to.) So I don't think the Mercedes example works. But I agree that it's very unlikely to be that being able to walk places makes you succeed. Could even be something as simple as enough people owning a few flats in their neighbourhood, which suddenly became super-valuable when lots of google employees showed up. That would look a lot like income mobility.