ramyaragupathy asked me recently how well I thought Seattle was mapped. One of the areas was very broad, POI’s which makes answering the question very difficult. Thinking about the question lead to what outside data source could we compare to OSM to get a sense of completeness.

I stumbled across the King County Health Department Restaurant Inspections. Every restaurant inspection, going back many years, is available in the counties open data repository.

The data needed some massaging, food inspectors seem to think that they shouldn’t limit themselves to just restaurants but any business that serves food, including schools, company cafeterias, the fried chicken (ugh) found in mini marts and food trucks. After removing businesses that didn’t match amenity=fast_food or restaurant or cafe it appears that OSM has 1,714 food service businesses vs. 3,680 inspected by the county or 47%, slightly less than half.

The actual results are most likely somewhere near 47% but OSM many have some closed businesses and the county’s list may be over stated (I may have keep businesses that should have been excluded.)

That brings up the question - what to do with all of the county’s data. It’s definitely not something I’d like to see imported, but it would be nice to see better coverage. What are your recommendations?

Clifford