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 <[email protected]>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 <[email protected]>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 >> >> _______________________________________________ >> Talk-GB mailing list >> [email protected] >> http://lists.openstreetmap.org/listinfo/talk-gb >> >> >
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