[Geodata] [Tiger] A few interesting observations on theTiger2007fedata

[Stephen Woodbridge]

Bob Basques wrote:
> 
> All,
>  
> I wonder if in the interests of making things simpler (Probably only for 
> us Techies) if some of these attributes be left as a spatial lookup 
> instead of binding as attributes.  I know that binding is a good 
> performance improvement, but the original owners/publishers of the data 
> seems to be more than just the census.  Does it make any sense to run 
> things, where possible, as spatial lookups, where the points are 
> spatially referenced inside of a ZIP polygon for example.

The problem is that zipcodes are NOT polygons they are carrier routes. 
ZCTA's that the Census produces are non-overlaying polygons that roughly 
approximate the area encompassed by a carrier route, but it is possible 
for carrier routes to do weird things like criss-cross one another.

> My suggestion has two big positives that I see, first there is much 
> better control over who manages the poly layers and the number of 
> possible iterations of something like this is endless, you could merge 
> the request with just about any polygon once a system were set up.  
> Second, the job of keeping everything up to date in a timely fashion 
> seems to be quite a task, any improments as far as automation would seem 
> like a positive to me.
>  
> Another possible option, would be to build the spatial lookup mechanism, 
> for the explicit task of building a attributed dataset.  This has the 
> benefit of being able to (more) easily keep things updated over time.
>  
> Just some (more) thoughts.

Right, but you have to convince the data producers of this, not us :)

-Steve W

> bobb
>  
> 
> 
>  >>> Stephen Frost <sfrost at snowman.net> wrote:
> Stephen, et al,
> 
> * Stephen Woodbridge (woodbri at swoodbridge.com) wrote:
>  > It is also important to note here that the zipcode info in Census is by 
>  > and large circa 1990 when the Census last used the USPS Zip+4 database 
>  > and did a mass merge/update of Tiger. This has an impact in a couple of 
>  > ways:
> 
> Census has their seperate ZCTA system, but I don't believe that
> means that the detailed per-segment Zip codes aren't ever updated..  It
> would be easy enough to check (not that I have) obviously, by looking at
> a recently added zip code and checking to find it in the latest Census
> data anywhere.  I had thought that the Zip codes were updated as part of
> the MAF improvment process at the detailed edge level though.
> 
> Just a thought.
> 
> Thanks,
> 
> Stephen