6 ms·

Whoa, whoa.... You're telling me there's a public data set of all taxi trip geolocation data with GPS precision? That's f'ing insane! I think there's a MUCH bi

by abalone 12y ago

Whoa, whoa.... You're telling me there's a public data set of all taxi trip geolocation data with GPS precision? That's f'ing insane! I think there's a MUCH bigger privacy issue here than what the author focuses on. Couldn't you deduce many passenger identities based on addresses? There's a lot of scenarios where passenger identities could be effectively de-anonymized, just based on GPS data. You could then use this data set to analyze their comings and goings. 1. For people who live alone in a single family home, you can pretty much completely track when and where they went by taxi. From this you can deduce a lot about their interests, lifestyle, workplace and schedule, private life, etc. It's profoundly invasive. 2. Even if there's a few people sharing an address, the other dropoff/pickup point can be used to narrow down the likelihood of who it is, especially when combined with other easily obtainable data. For example if you knew an employee (e.g. that cute barista) lived in a certain neighborhood you could track their trips to/from work and deduce their home address. Or if you knew there was only one senior citizen (or Muslim, etc.) living in a building, a regular trip to a senior center (or mosque) would reveal when their apartment is vacant. Or if there's only one young man in a building, a single trip home from a gay bar could out them. Holy shit.. can you imagine someone just plotting all the trips from a single gay bar? Listing off all the connected residential addresses? And not only that, any subsequent trips home from those addresses the next morning? Taking the walk of shame to a whole new level! Likewise trips could be used to deduce affairs and other deceptions by fellow residents. "You said you were working late, but the only taxi trip to our building that night was from a bar." This is just off the top of my head.. I feel I could go on for hours listing all the possible ways this data set could be exploited. How is this not front page New York Times???

yid 12y ago
> Holy shit.. can you imagine someone just plotting all the trips from a single gay bar? Listing off all the connected residential addresses? And not only that, any subsequent trips home from those addresses the next morning? Taking the walk of shame to a whole new level! There are some weird assumptions going on here, in addition to the fact that you grossly overestimate the precision to which GPS data can de-anonymize individuals who are using a shared, public transport mechanism in a city as densely crowded as NYC. The density of people and businesses alone makes individual identification difficult, not to mention weak GPS signals and low accuracy with skyscrapers every hundred yards. Is there any evidence that the logs have enough accuracy to do what you're claiming, or are you just wildly speculating?
- abalone 12y ago
  What is the weird assumption? That GPS is precise enough to identify addresses? Not all of NYC has skyscrapers every hundred yards.. that's only portions of Manhattan. It's 5 boroughs.
  - danso 12y ago
    Oh my god. You really think there are poor people in Brooklyn or the Bronx who, nevermind being able to afford a place in which they are the only people within 50m of 10 other families, can regularly go into the city at a given time in a taxi? The commute traffic into Manhattan is hellish -- who in their right mind would use it to get to work? A taxi is not a replacement for a car, it is a luxury, and it is expensive. Another poor assumption: that people get dropped off right in front of their homes. Uh, no. I take taxis several times a month to get home. I'm never, never able to get dropped off right in front of my apartment because traffic is dense enough and the one-way streets add another 0.50 to $1 when I can just hop off and take a pleasant two minute walk up the corner. edit: And another poor assumption: that there is one easily locatable gay bar within a vicinity of where people hail a taxi (again, it won't always, or even mostly, be in front of the exact place they just walked out of) or that, after leaving a bar, people go straight to their own home.
    - abalone 12y ago
      Plenty of people take taxis between Manhattan and Brooklyn. A significant percentage of rides home to Brooklyn from Manhattan bars at night are in cabs, for example. The fact that you think everyone in Brooklyn is "poor" or that only rich people take cabs shows how inaccurate your knowledge of NYC is. I've tried to address your other concerns in other comments. Just because you don't get dropped off at your place doesn't mean no-one else in NYC does ever.
Hominem 12y ago
I think the way cabs actually operate in NYC makes this practically impossible unless you already have some details such as the lat/Lon of dropoff and pickup and time of the stops. I'm assuming the data is for yellow cabs and the new lime green "boro cabs" you hail on the street, not "car service" cars where you schedule a pickup and dropoff to specific addresses. Most bars in Manhattan are storefronts in 3-4 story residential buildings. There are apartments above and they are surrounded by other buildings with apartments and businesses. I don't think you could identify a bar. Now strip clubs on the other hand are required by law to be tucked away in isolated locations. Might be possible to identify a strip club. When you hail a cab, and many times when you get dropped off, it happens on a corner, perhaps over a block away, where it is easier to find a free cab. Most cabs are in Manhattan, not a lot of single family homes. Single family homes in the outer boroughs will have almost no yellow cab coverage for pickup and finding a cab that will take you out of Manhattan can be dicey, although I guess those lime green cabs are meant to address that. SI, the Bronx and huge swaths of Brooklyn and Queens pickups will be almost non existant, people going from the outer boroughs will most likely use a car service. I will certainly be checking to see if I can identify any of my rides.
- abalone 12y ago
  > unless you already have some details such as the lat/Lon of dropoff and pickup and time of the stops. These are literally columns in the data set. To quote the original post: Each file has about 14 million rows, and each row contains medallion, hack license, vendor id, rate code, store and forward flag, pickup date/time dropoff date/time, passenger count, trip time in seconds, trip distance, and latitude/longitude coordinates for the pickup and dropoff locations. [1] You're right that a lot of cab pickups/dropoffs happen a few doors down from the actual location, and that there aren't a lot of single family homes in Manhattan. But that doesn't negate what I'm saying. Even if only 20% of rides involve the actual location, that's still an awful lot of potential privacy violations. And even if there are zero single family homes involved, that was only the first scenario of numerous ones I mentioned. [1] http://chriswhong.com/open-data/foil_nyc_taxi/ http://chriswhong.com/open-data/foil_nyc_taxi/
  - 12y ago
saraid216 12y ago
> How is this not front page New York Times??? Because it's unproven. If no one beats me to it, I'll grab a dump of the data and look myself. But in the abstract, I agree; there's a non-zero risk of being able to identify passengers from the logs. This makes for an interesting ethical problem: should this data have been made available? It becomes much, much less useful without those coordinates. Which is more important? Government transparency or citizen privacy?
- abalone 12y ago
  I don't even get how this is government transparency. That's like saying everyone's cell phone records ("just the metadata") should be published, minus names, because telecom is regulated.
  - saraid216 12y ago
    Government transparency is largely about opening the data they have available to them up to the public in a consumable way. FOIL requests like the one Whong filed are essentially the second-oldest way they have done this. (The oldest being, well, just asking directly.) So, yes. It can definitely be argued that cell phone records, insofar as they are shared with the government in the first place, should be published. A simple counterargument would be that cellphones do not consume a public resource, unlike the way taxis consume road space, so there is no reason to share said data with the government and consequently the public. But as a rule of thumb, government transparency is that any data the government has ultimately belongs to the public. It's not a matter of regulation.
    - eric_bullington 12y ago
      >A simple counterargument would be that cellphones do not consume a public resource, unlike the way taxis consume road space, so there is no reason to share said data with the government and consequently the public. That argument would be incorrect, since all cell phones run over a public resource: the airwaves. These airwaves are licensed by the FCC licenses to private companies, but (in theory at least) the public retains ownership of those airwaves.
gaadd33 12y ago
It would be interesting to see how many GPS pairs map to a single address not at an intersection. I would guess most people don't go directly to their address but to the nearest cross streets since its cheaper and faster.
danso 12y ago
Do you live in New York? 1. New York taxis are hailed from the street. AFAIK, you can't call a medallion taxi to your home for pickup. So that makes impractical the idea of a single-family home (which is pretty damn rare in New York) being narrowed as the sole user of a particular taxi. 2. Um, no, again. First of all, are you fucking kidding me? A barista, taking a taxi on a daily, or even weekly basis, in a city with U.S. most comprehensive subway and bus system? A barista. But I'm not being nit-picky here, taking taxis on a regular basis is within the means of the rich, only. And how many rich people do you think live in non-dense areas (i.e. areas in which 100-500 people could be within a certain lat/long)? And how many people in that income bracket would not take a private car? Do you really imagine there to be a significant number of New Yorkers who take taxis at a regular time, to a regular place, from a residence in which there aren't dozens, if not hundreds of people, within a 50m radius? Again, you realize gay bars are in densely populated areas, and a taxi right in front of a gay bar could be determined to come from a large number of bars, nevermind that it is not always the case that you call for a taxi in front of the place you just stepped out. Sometimes you call it from a cross-street, or up-street to better your chances. And of course there's the detail of the delayed release time of these records. It's as if you took all the stock privacy-violation concerns with surveillance and applied them to a situation in which the real-world details don't make any sense.

by abalone 12y ago

yid 12y ago

> Holy shit.. can you imagine someone just plotting all the trips from a single gay bar? Listing off all the connected residential addresses? And not only that, any subsequent trips home from those addresses the next morning? Taking the walk of shame to a whole new level! There are some weird assumptions going on here, in addition to the fact that you grossly overestimate the precision to which GPS data can de-anonymize individuals who are using a shared, public transport mechanism in a city as densely crowded as NYC. The density of people and businesses alone makes individual identification difficult, not to mention weak GPS signals and low accuracy with skyscrapers every hundred yards. Is there any evidence that the logs have enough accuracy to do what you're claiming, or are you just wildly speculating?

abalone 12y ago
What is the weird assumption? That GPS is precise enough to identify addresses? Not all of NYC has skyscrapers every hundred yards.. that's only portions of Manhattan. It's 5 boroughs.
- danso 12y ago
  Oh my god. You really think there are poor people in Brooklyn or the Bronx who, nevermind being able to afford a place in which they are the only people within 50m of 10 other families, can regularly go into the city at a given time in a taxi? The commute traffic into Manhattan is hellish -- who in their right mind would use it to get to work? A taxi is not a replacement for a car, it is a luxury, and it is expensive. Another poor assumption: that people get dropped off right in front of their homes. Uh, no. I take taxis several times a month to get home. I'm never, never able to get dropped off right in front of my apartment because traffic is dense enough and the one-way streets add another 0.50 to $1 when I can just hop off and take a pleasant two minute walk up the corner. edit: And another poor assumption: that there is one easily locatable gay bar within a vicinity of where people hail a taxi (again, it won't always, or even mostly, be in front of the exact place they just walked out of) or that, after leaving a bar, people go straight to their own home.
  - abalone 12y ago
    Plenty of people take taxis between Manhattan and Brooklyn. A significant percentage of rides home to Brooklyn from Manhattan bars at night are in cabs, for example. The fact that you think everyone in Brooklyn is "poor" or that only rich people take cabs shows how inaccurate your knowledge of NYC is. I've tried to address your other concerns in other comments. Just because you don't get dropped off at your place doesn't mean no-one else in NYC does ever.

Hominem 12y ago

I think the way cabs actually operate in NYC makes this practically impossible unless you already have some details such as the lat/Lon of dropoff and pickup and time of the stops. I'm assuming the data is for yellow cabs and the new lime green "boro cabs" you hail on the street, not "car service" cars where you schedule a pickup and dropoff to specific addresses. Most bars in Manhattan are storefronts in 3-4 story residential buildings. There are apartments above and they are surrounded by other buildings with apartments and businesses. I don't think you could identify a bar. Now strip clubs on the other hand are required by law to be tucked away in isolated locations. Might be possible to identify a strip club. When you hail a cab, and many times when you get dropped off, it happens on a corner, perhaps over a block away, where it is easier to find a free cab. Most cabs are in Manhattan, not a lot of single family homes. Single family homes in the outer boroughs will have almost no yellow cab coverage for pickup and finding a cab that will take you out of Manhattan can be dicey, although I guess those lime green cabs are meant to address that. SI, the Bronx and huge swaths of Brooklyn and Queens pickups will be almost non existant, people going from the outer boroughs will most likely use a car service. I will certainly be checking to see if I can identify any of my rides.

abalone 12y ago
> unless you already have some details such as the lat/Lon of dropoff and pickup and time of the stops. These are literally columns in the data set. To quote the original post: Each file has about 14 million rows, and each row contains medallion, hack license, vendor id, rate code, store and forward flag, pickup date/time dropoff date/time, passenger count, trip time in seconds, trip distance, and latitude/longitude coordinates for the pickup and dropoff locations. [1] You're right that a lot of cab pickups/dropoffs happen a few doors down from the actual location, and that there aren't a lot of single family homes in Manhattan. But that doesn't negate what I'm saying. Even if only 20% of rides involve the actual location, that's still an awful lot of potential privacy violations. And even if there are zero single family homes involved, that was only the first scenario of numerous ones I mentioned. [1] http://chriswhong.com/open-data/foil_nyc_taxi/ http://chriswhong.com/open-data/foil_nyc_taxi/
- 12y ago

saraid216 12y ago

> How is this not front page New York Times??? Because it's unproven. If no one beats me to it, I'll grab a dump of the data and look myself. But in the abstract, I agree; there's a non-zero risk of being able to identify passengers from the logs. This makes for an interesting ethical problem: should this data have been made available? It becomes much, much less useful without those coordinates. Which is more important? Government transparency or citizen privacy?

abalone 12y ago
I don't even get how this is government transparency. That's like saying everyone's cell phone records ("just the metadata") should be published, minus names, because telecom is regulated.
- saraid216 12y ago
  Government transparency is largely about opening the data they have available to them up to the public in a consumable way. FOIL requests like the one Whong filed are essentially the second-oldest way they have done this. (The oldest being, well, just asking directly.) So, yes. It can definitely be argued that cell phone records, insofar as they are shared with the government in the first place, should be published. A simple counterargument would be that cellphones do not consume a public resource, unlike the way taxis consume road space, so there is no reason to share said data with the government and consequently the public. But as a rule of thumb, government transparency is that any data the government has ultimately belongs to the public. It's not a matter of regulation.
  - eric_bullington 12y ago
    >A simple counterargument would be that cellphones do not consume a public resource, unlike the way taxis consume road space, so there is no reason to share said data with the government and consequently the public. That argument would be incorrect, since all cell phones run over a public resource: the airwaves. These airwaves are licensed by the FCC licenses to private companies, but (in theory at least) the public retains ownership of those airwaves.

gaadd33 12y ago

It would be interesting to see how many GPS pairs map to a single address not at an intersection. I would guess most people don't go directly to their address but to the nearest cross streets since its cheaper and faster.

danso 12y ago

Do you live in New York? 1. New York taxis are hailed from the street. AFAIK, you can't call a medallion taxi to your home for pickup. So that makes impractical the idea of a single-family home (which is pretty damn rare in New York) being narrowed as the sole user of a particular taxi. 2. Um, no, again. First of all, are you fucking kidding me? A barista, taking a taxi on a daily, or even weekly basis, in a city with U.S. most comprehensive subway and bus system? A barista. But I'm not being nit-picky here, taking taxis on a regular basis is within the means of the rich, only. And how many rich people do you think live in non-dense areas (i.e. areas in which 100-500 people could be within a certain lat/long)? And how many people in that income bracket would not take a private car? Do you really imagine there to be a significant number of New Yorkers who take taxis at a regular time, to a regular place, from a residence in which there aren't dozens, if not hundreds of people, within a 50m radius? Again, you realize gay bars are in densely populated areas, and a taxi right in front of a gay bar could be determined to come from a large number of bars, nevermind that it is not always the case that you call for a taxi in front of the place you just stepped out. Sometimes you call it from a cross-street, or up-street to better your chances. And of course there's the detail of the delayed release time of these records. It's as if you took all the stock privacy-violation concerns with surveillance and applied them to a situation in which the real-world details don't make any sense.