allmapdata.com - Understanding data - Postcode points & geocoders
Postcode point and geocoder data sets are postcode lists with postcode coordinates (postcode x & y values) to allow you to add your own information to the map - this could be a coloured symbol where each of your items of interest is located - eg. your outlets, customers, patients, depots etc. Geocoding is simply adding geography to your postcode (or other location information) to enable your mapping system to know where to place the postcode point on the map. Postcode point files and geocoders include address, postcode or zip code point files with the appropriate map coordinates in a projection appropriate to the geographic coverage of the data.
To help you choose the best postcode point list or geocoder for your project, it is important to understand the postcode geography for the country you are working with. For example, in Britain there are unit postcode points, postcode sector points, postcode district points and postcode area points. Unit postcode point files such as ForGIS points have a target accuracy of within 1m of the property closest to the centre of the postcode, whereas postcode sector points are positioned at the centre (centroid) of the postcode sector. Allmapdata postcode sectors provide population centred postcode centroids so your data will be placed in a position where a high proportion of the population of that postcode sector live, rather than in the mathematical centre which could be a barren, unpopulated area.
To map your data, the postcode in your records must match the postcodes in the geocoding postcode centroid file, so allmapdata offers a range of address management products to clean and correct addresses in your existing data and to capture new addresses correctly for future use.
Postcode geography across the world is structured differently and location information may be less easily accessible for non-UK countries. In some countries, the postcode system is less detailed than in the UK and USA, so the municipality or other administrative unit might locate your addressed data more precisely on the map. You can also geocode with a more broad-brush approach by simply assigning grid references (or coordinates) to each town and matching your data at city or town level. For these types of geocoder, see the gazetteer section of the allmapdata on-line data catalogue.
Need to understand more about which level of geography or type of geocoding postcode list is best for you? Contact us now to discuss your mapping data requirements.