APHG Day 9

Space-Time Compression

Expressions of the extent to which improvements in transportation and communication have reduced the friction of distance and permitted, for example, the very rapid diffusion of ideas across space.

Law of Retail Gravitation

Any gravity model of shopping behavior, such as Reilly's Breaking-Point Law or the potential model when applied to multiple stores or shopping centers.

Potential Model

A measurement of the total interaction opportunities available under gravity model assumptions to a center in a multicenter system

Friction of Distance

A measure of the retarding or restricting effect of distance on spatial interaction. Generally, the greater the distance, the greater the "friction" and the less the interaction, or the greater the cost of achieving the exchange.

Movement Bias

Any aggregate control on or regularity of movement of people, commodities, or communication. (Included are distance bias, direction bias, and network bias.)

Links

A transportation or communication connection or route within a network

Reilly's Breaking-Point Law

A law of retail gravitation proposed by William J. Reilly that finds the breaking point or boundary line of the market area functional regions around two cities' trade areas. It predicts that consumers will make shopping trips to the city within the market area in which they live.

Gravity Model

A mathematical prediction of the interaction between two places as a function of their size (or other measure of attractiveness to interaction) and some measure of the distance separating them.

Network Bias

The view that the pattern of links in a network will affect the likelihood of flows between specific nodes.

First Law of Geography

(Syn: distance decay) "Everything is related to everything else, but near things are more related than distant things"- American geographer Waldo Tobler

Network

the areal pattern of sets of places and the routes (links) connecting them along which movement or communication can take place.

Nodes

An origin, destination, or intersection place in a communication or transportation network.

Intervening Opportunities

The concept that closer opportunities will materially reduce the attractive of interaction with more distant - even slightly better - alternatives; a closer alternative source of supply between a demand point and the original source of supply

Complementarity

The actual or potential relationship of two places or regions that each produce different goods or services for which the other has an effective demand, resulting in and exchange between the locales

Spatial Interactions

The movements (of people, goods, information, etc.) between different places; an indication of contact and interdependence between different geographic locations or areas.

Distance Decay

The declining intensity of any spatial interaction with increasing distance from its point of origin.

Transferability

Acceptable costs of a spatial exchange; the cost of moving a commodity relative to the ability of the commodity to bear that cost.

Barriers

A geographic feature that impedes spatial interaction, either by blocking it totally, slowing it down, or redirecting it. They may be physical, socio-cultural or psychological.