3.3 Mortality

We now turn to the concept of mortality, which when applied in the human context, is the ratio of the number of deaths to the surviving population. To illustrate this, let us consider the population in a geographical area. Let us say that there are 100,000 people in the area on the day in question. If there were ten deaths in all on that day, the mortality rate was 10/100,000, or 0.0001. Actuaries analyze the mortality of a population with respect to their age. They measure the proportion of the population that die within one, two, three ....n years. A plot of these mortality values would be similar to Figure3.3, Element A (which refers to equipment component failures). In the first part of the curve (the so-called infant mortality section) the mortality rate keeps falling. Ababy has a high chance of dying at birth, and the longer it survives, the greater the chance that it will continue to live. After the first few days or weeks, the mortality rate levels out, and for the next 50-70 years, it is fairly constant. People die randomly, due to events such as road accidents, food poisoning, homicides, cancer, heart disease, or other reasons. Depending on their lifestyles, diet, race, and sex, from about 50 years on the mortality starts to rise. As they get older, they become susceptible to more diseases, their bones tend to become brittle, and their general resistance becomes lower. Not many people live up to 100 years,...