Every analysis rests on where the sites are. Sloc records how each one was placed and how confident it is, so you can find the ones worth checking instead of trusting the whole file - or doubting it.

The Location columns

On the Data page, expand the Location column group in the site table. Alongside the address, it holds what Sloc did and what it got:

• Location method - how the site was placed: postcode geocoding, address geocoding, coordinates from your file, or a position you set by hand.

• Location input - what was actually looked up. Worth a glance when a result surprises you; the input is usually the reason.

• Location type - how precise the match is. A rooftop or address-level match is a building; a postcode or locality match is an area, and the pin sits at its centre.

• Match confidence - how sure the geocoder is. Exact is what you want; anything less is a site to look at.

• Urbanicity and GHSL Settlement Class - whether the site sits in a city, a town or open country. Useful for sanity-checking catchments, and for setting different ones by area.

Every column filters, so Match confidence is not Exact, or Location type is a postcode rather than an address, gives you a worklist in seconds.

One site in detail

Open a site with the pencil and expand Location and geocoding details. It lays out the whole record for that site - method, input, type, confidence, the address as the geocoder returned it, the administrative area, urbanicity and the coordinates - with the provider named at the top right.

Google Maps and Street View links open the coordinates in a new tab, which is the fastest way to see whether the pin is on the shop or on the roundabout outside it.

Fixing one by looking it up

In the same panel, Search for an address or place looks up any address and offers matches as you type. Pick one and the pin moves there; or click the map directly if you know the spot better than the address does. Update site saves it, and the location method changes to record that it was set by hand.

More on the editor itself is in how to edit a site's details and location.

Pro tips

• Check the quality columns before you run anything. A site placed at a postcode centroid can sit several hundred metres from the shop, which is enough to move a 1km market.

• Sort by match confidence and work down. The weak matches are nearly always a handful of sites, not the file.

• Postcodes give a tidy-looking result everywhere, which is the trap. An exact postcode match is still only as precise as the postcode.

• Street View is the quickest proof that a site is where you say it is - and the quickest way to find the ones that aren't.