Name transliteration and diacritics in address data
The same street name can be written correctly in several different scripts and spellings. Matching addresses across these variants is a genuine data quality challenge.
Blog topic
Data quality (page 4)
Coverage by country, accuracy measurements, and how to read the precision and confidence in each answer.
Why coordinate rounding matters more than people think
Trimming decimal places on a coordinate looks harmless, but each digit represents real distance on the ground, and rounding too aggressively can move a point by meters or kilometers.
Address parsing ambiguity: apartments, units and PO boxes
A single address string can hide several distinct pieces of meaning, and the same abbreviation can mean different things in different countries. Parsing it correctly is harder than it looks.
Coordinate reference systems: why WGS84 is the default
Every set of coordinates is defined relative to some model of the Earth's shape. WGS84 became the default for GPS and web mapping for practical reasons worth understanding.
How disputed territories are handled in location data
Some coordinates sit in places where more than one government claims sovereignty. Location data has to describe reality on the ground without taking a political side.
ISO 3166-1 and 3166-2 codes, and where they get confusing
Country codes and subdivision codes look simple until you hit the exceptions. Here is what ISO 3166-1 and 3166-2 actually cover, and where confusion creeps in.
Countries with no house numbering system
Not every country organizes addresses around a street name and a house number. Several use entirely different schemes, and geocoding has to accommodate that.
Postal code granularity: the UK versus the US versus everywhere else
A UK postcode can identify a single street or even a handful of buildings. A US ZIP code covers a much larger area. Postal granularity varies enormously by country.
How elevation accuracy changes with terrain type
Elevation data is not equally accurate everywhere. Flat, open terrain is easy to measure precisely, while steep or heavily vegetated ground is not.
Elevation data resolution: what "463 meters" really means
An elevation value is not measured at the exact point you asked for, it comes from a sample grid with a stated resolution. That resolution changes what the number means.
Only Data quality, as it is published.
Subscribe to Data quality