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Stop using zip codes for geospatial analysis (2019)

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Re: Stop using zip codes for geospatial analysis (2019)

#71

Post by mattforrest »

mywittyname wrote: post #51
cogman10 wrote: post #20

Earlier quoted context omitted.

Zip codes (in the US) are machine readable numbers a mail sorter can use to send a parcel to the right delivery truck for final delivery. In the US, they represent the hierarchy of postal centers with the most significant digit representing the primary hub for a region and the smallest number the actual post office that will be in charge of delivering the letter (or truck if you do the extended post code). They don't…

> For some smaller population zip codes you can practically just put the name and zip code down and achieve delivery. A 5+4 formatted ZIP code maps to just a handful of addresses. In cities with larger populations, the +4 could map to a single building, and in more sparely populated place, it might include houses on a handful of roads. For smaller datasets, ZIP+4 might as well be a unique household identifier. I just…

Yeah but we have that already in the census hierarchy. Plus you have to pay to access Zip+4 geospatial data and it changes sometime as frequently as quarterly

Re: Stop using zip codes for geospatial analysis (2019)

#72

Post by mattforrest »

Spivak wrote: post #35
cogman10 wrote: post #20

Earlier quoted context omitted.

Zip codes (in the US) are machine readable numbers a mail sorter can use to send a parcel to the right delivery truck for final delivery. In the US, they represent the hierarchy of postal centers with the most significant digit representing the primary hub for a region and the smallest number the actual post office that will be in charge of delivering the letter (or truck if you do the extended post code). They don't…

Right but this ends up being a good approximation for geography because the reality of logistics is that you end up doing a cute n-ary search of the geography. When you know the regional hub you can say for certain a huge chunk of the US the zip code doesn't represent. And then you keep n-secting. Sometimes the land-mass you get at the end is specific enough for your uses. You're not going to wind up with a situation…

Just use a spatial query. That’s what they are made for.

Re: Stop using zip codes for geospatial analysis (2019)

#73

Post by killjoywashere »

jonas21 wrote: post #14

ZIP codes are an emergent property of the mail delivery system. While the author might consider this a bad thing, this makes them "good enough" on multiple axes in practice. They tend to be: - Well-known (everybody knows their zip code) - Easily extracted (they're part of every address, no geocoding required) - Uniform-enough (not perfect, but in most cases close) - Granular-enough - Contiguous-enough by travel time…

ZIPs are also specifically used in a variety of medical, epidemiologic, public health contexts and HHS has explicit, fairly fine-grained rules on their use: https://www.hhs.gov/hipaa/for-professionals/special-topics/d...

Re: Stop using zip codes for geospatial analysis (2019)

#74

Post by paganel »

freyfogle wrote: post #66

There are many problems with zip codes / postal codes but the biggest two we see are: a. Excel treats them as numbers instead of strings of digits and thus drops the leading 0 b. Developers make assumptions about postal codes based on how they work (or more usually how the developer incorrectly thinks they work) in their own country and these assumptions absolutely do NOT hold in other countries. A relevant guide to…

Also, "everybody" knows their zip-code/postal-code is mostly an American/British thing, I still remember my British former boss asking me about my zip-code about 20 years ago (I live in Romania, we were implementing the first google-maps-based mashup in this country) and me answering that I have no idea, and that no-one around these parts really knows his/her postal-code. We do know our address, though, or used to, before we had smart-phones.

Re: Stop using zip codes for geospatial analysis (2019)

#76

Post by mattforrest »

mcphage wrote: post #30
jihadjihad wrote: post #4

To put it in plain mathematical language, ZIP codes are not defined as polygons [0]. The consequence is that performing any analysis with an assumption that ZIP codes are polygons is bound to be error-prone. 0: https://manifold.net/doc/mfd8/zip_codes_are_not_areas.htm

> The consequence is that performing any analysis with an assumption that ZIP codes are polygons is bound to be error-prone. Yeah, but any analysis you're likely to perform is approximate enough that the fact that ZIP codes aren't polygons is basically a rounding error. Plus, it's a lot easier to get ZIP codes, and they're more reliably correct, so you might still get better results, than you would going with another…

They aren’t reliable correct actually. The boundaries that the Census publishes are called Zip Code Tabulation Areas which are approximations of zip codes and include overlaps.

Re: Stop using zip codes for geospatial analysis (2019)

#79

Post by paraboli »

diggan wrote: post #33
jpjoi wrote: post #8

Zip codes are just weird to use for anything other than mail in general because they’re set up based off infrastructure. CGP Grey has a great video on this: https://m.youtube.com/watch?v=1K5oDtVAYzk

I've noticed more and more super/hypermarkets started asking for your zip/postal code sometime during self-checkout. I'm guessing they use these as approximations about where people travel from, so they can evaluate if to open more stores closer to popular areas, or something like that. Pretty sure there is more use cases for postal codes too.

They use bulk mail to send out flyers, coupons, and can use zip codes to AB test these.
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