[Talk-GB] Postcode data

[Rob Nickerson]

That's an interesting list for anyone who is concerned with data cleansing!
Some of the results are because only the first part of a postcode has been
entered, however even these have numerous formats (e.g. CV3, CV3 ???, CV3
///). For the other errors, it tends to be typos (e.g. CO!6 7BJ, where ! is
a probably a typo of 1 - Shift+1=!), but there are also road names,
numbers, and web URLs in the postcode tag.

Would it be possible to create a list of these where we could add the
correct postcode in a new column and then upload the new data into OSM?

Rob



On 1 March 2013 17:24, Aidan McGinley <aidmcgin+openstreetmap at gmail.com>wrote:

> * How accurate is the data already in OSM?
> Interesting question Rob, as of today there's approximately 200,000 ways
> or nodes tagged with postcodes in OSM, this is made up of about 29,000
> unique postcodes.  Those numbers are not 100% accurate as my bounding box
> for getting the data overlaps a bit with France and Ireland. I've removed
> the obvious French postcodes (5 digits) there might be a few I missed
> although I'm pretty sure the extras don't skew the numbers too much.
>
> I've compared the unique values from that list with the ONS dataset
> (excluding terminated postcodes) and come up with the list linked below [1]
>
> There's 1119 unique invalid postcodes, which of of course doesn't account
> for ways or nodes that are incorrectly tagged with a valid postcode but is
> a useful stat nonetheless.  It should also be relatively easy to get those
> cleaned up I would think.
> Couple of notes about the data, there are a few postcodes that look like
> they are valid (e.g. BR3 1AZ, WC2H 9BD) but they have in fact got some
> invalid characters at the end that are not visible so that's why they are
> listed.  It also includes postcodes in lowercase as well since it breaks
> from the convention of uppercase postcodes, you could argue that they
> should be in or out, but it was easier to leave them in.
>
> [1]
> https://docs.google.com/file/d/0B0viaV_xKHyCNmJDY1A1X092Zkk/edit?usp=sharing
>
> On 28 February 2013 23:44, Rob Nickerson <rob.j.nickerson at gmail.com>wrote:
>
>> Interestingly out of the 95 you also identified 2 postcodes that are
>> incorrect in OSM... raising the obvious questions:
>>
>> * How accurate is the data already in OSM?
>> * Should imports be compared to 100% accuracy or a more realistic measure
>> of OSM accuracy?
>>
>> Rob
>>
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