The traditional retail hierarchy
An important point about the concept of hierarchy is that competition is as much vertical as horizontal. This means that levels of the hierarchy compete with those above and below (vertical) as much if not more than they do with similar levels (horizontal), and this applies particularly in the retail area. Take, for example, a family living on the edge of a small town of 35,000 population. For food and other routine shopping they will probably spend most at the nearest supermarket, but they could also shop at a close by convenience store, or at a larger superstore on the edge of the large town of 150,000 population which they occasionally visit for clothes shopping. In this case the competition for food is between the local, district and regional levels of a single spatial hierarchy. They are less likely to visit a supermarket in the neighbouring town of similar size, although this may well happen, particularly if they work there or have family links.