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IAI Actuarial Core Principles · Risk Modelling and Survival Analysis · Estimation procedures for lifetime distributions

In a mortality investigation of a group of lives, the central exposed to risk E^c_x is best described as:

Central exposed to risk is the total time, in person-years, that lives are observed at age x, counting both survivors and those who die. It is the denominator of the central mortality rate, so it measures time lived, not a head count of lives.

  1. AThe number of lives alive at exact age x at the start of the investigation
  2. BThe total time spent under observation by lives at age x, whether or not they die, in yearsCorrect
  3. CThe number of deaths observed divided by the number of survivors at the end
  4. DThe total time lived by those lives who die at age x
  5. The number of lives entering the investigation at age x

Explanation

Central exposed to risk measures total person-years observed at age x, including time lived by those who survive and those who die. It is the denominator used for the central rate of mortality. The other options count lives or only part of the time.

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