Social Sciences and History / Unit 12 SSH 1121 worked example, 60 to 90 seconds
Rank-Size Against Primacy: Reading a Country's Cities
The idea
The exam gives city sizes and asks whether a country follows the rank-size rule or shows primacy, and the anchor's definitions decide it. The rank-size rule is a statistical regularity in the size distribution of cities: the second city is about half the largest, the third a third, and so on down the ranks. Primacy is the condition in which the largest city is disproportionately large relative to the second and third. A primate city is the largest settlement when it has more than twice as many people as the second, and Finlayson adds that it represents the national culture; his examples are Montevideo, home to over half of Uruguay's people, and Mexico City. Centrality is a city's functional dominance within an urban system, the interdependent set of settlements in a region.
In practice
Given "ten million, five million, three point three million", rank-size. Given "ten million, three million, two million", primacy, and the largest is a primate city. Given "two cities of six and five million", neither. Divide the largest by the second; more than two means primate, about two means rank-size. Given "Germany, where Berlin is about twice Hamburg", Finlayson's borderline.
Where people slip
The trap is the threshold: more than twice, not merely the largest. The second trap is reading primacy as a virtue or a fault; the anchor defines a condition, and Finlayson notes many countries have no primate city.
Your place on the trail
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