Email client is being screwy or I'd reply inline
What sample size do you feel is needed to be statistically significant? I am confident this reaches statistical significance. Are you proposing that the characteristics of the imports vary by day of the week? As for a statement, 55% of imported building ways share geometry with other imported building ways. 21% of building ways added in the same timespan from randomly selected changesets share geometry with other building ways of the same type. What do you mean by differentiate from the rest? I'm not treating the randomly selected buildings any differently. I performed two analysis, one for cadastre edits and one for typical edits. You need to be able to compare with existing data. At this point I might do one more stats run to address any concerns, but I'm not going to continue to reanalyze the same data and get the same results. I may look at some different analysis, but that'll be on sub-populations, etc From: Olivier Croquette [mailto:m...@ocroquette.de] Sent: Thursday, September 27, 2012 5:58 AM To: Paul Norman Cc: 'Frederik Ramm'; talk@openstreetmap.org Subject: Re: [OSM-talk] All you've ever wanted to know about the french cadastre On Sep 27, 2012, at 2:18 AM, Paul Norman wrote: This is not an example that you only find after a long search; it is a typical cadastre import building. Until you can back up your claim with solid numbers, your claim, more specifically the word"typical", is just FUD. Furthermore it can hurt many hard working french contributors, who for a single city spent dozens of hours integrating the cadaster into OSM. Time for some numbers then... Detailed data is available upon request. Thanks Paul for taking the time to give some numbers. I don't understand also the technical details but hopefully well enough to provide some feedback that makes sense :) Looking at your examples, I can see that some buildings have a geometry that doesn't seem to be in line with the reality. However, like other persons mentioned here already, the only way to find out if this is OK is to check with a survey. The problem is however real. I know that our french OSM gurus have some checks for the cadaster import, but I don't know if it catches this kind of potential errors. Still, your analysis still doesn't quantify it well enough to entitle it "typical". 1 day of data is really not enough to be representative. Also, it's impossible to find automatically if adjacent building ways should be joined or not ("wall" issue, adjacent but separate buildings.). I am not saying it's not a problem, and I am not saying it's not typical, I am just saying there isn't enough proof to say that yet. A significant number of cadastre imported buildings consist of multiple ways, such as in the example Frederik gave. Could you summarize it in more simple wording and an exact number ? For instance: "10% of the new buildings imported between . and . share some ways with other buildings that have the same tags." Also, I didn't understand who you differentiate the cadaster imports from the rest. Cheers Olivier
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