To a demographer, a group of people that begin something at the same time is known as:
a) a cohort.
b) a team.
c) a dependency ratio.
d) a transnational migrant.
e) a baby boom.

a) a cohort.

Explanation:

Cohort is a term which is used in marketing, statistics and demography. It describes a group of people who share a defining characteristic - a group of people who share a common event. This type of data is more accurate than period data, also used by the demographers.

On the other side, cohort data has some disadvantages. It can take a long amount of time to collect all the necessary data for a study. Also it can be really costly, and a lot of money is necessary to conduct a successful research. Two important cohort study types are prospective and retrospective cohort study.

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