Answer:
Urban Primacy is when one city is dominantly large in a group of cities. For example, Thailand exhibits urban primacy because Bangkok is several times larger than the next largest city. Usually when a largest city is over twice as large as the next city, this would constitute urban primacy. Other measures are more rigorous whereby a city is only primate when it is at least 3 times larger than the next two cities combined. Primacy is almost always calculated using this kind of population-size ratio. Ideally metropolitan level populations are used so as to avoid dividing the largest city by an adjacent centre.
