Gravity modelling, or spatial interaction modelling, lies at the heart of many a location
analysis. It is a technique which uses a mathematical model to predict the level of
customer trips between residential zones and facilities, such as store locations.

The technique is used by several of the UK’s leading grocery and high street retailers
in the planning of store networks and predicting the expected levels of business at
new sites and is applicable across a wide range of markets from banking to healthcare
to leisure to public services such as post office locations.

Gravity models can provide the answers to such questions as:

• What is the impact that a new site or closure has on existing outlets, including those operated by competitors?
• What is the effect on market share and accessibility to services, residential zone by residential zone of facility openings and closures?
• What is the shape and extent of each facilities catchment and how does this overlap with the catchment of nearby facilities?

Modelling the spatial dynamics of demand and supply