If the boundary of an area has changed, what problem occurs when comparing population change?

Correct answer: The base area and population may change

Direct answer: Option A. Population comparisons require the geographical units being compared to remain consistent. If an area gains or loses villages, towns or other territory because its boundary changes, the population total is affected by both real demographic change and the altered area definition. A rise in population may therefore result partly from added territory, while a fall may result partly from territory being removed. Option A is correct because both the base area and the population counted within it may change. Option B is wrong because a boundary change does not make births disappear. Option C is wrong because people can still migrate across or within the new boundary. Option D is wrong because the concept of death rate does not change, although the data may need recalculation for the new area. To compare fairly, old data should be adjusted to the same boundary wherever possible. Memory cue: compare like with like—same territory, same period and same definitions.