Billeter J

Billeter J is in of statistics professor Ernst Peter Billeter imported measure for the comparative description of demographic aging.

Definition

Billeter suggests representing the age structure of a population with the help of the yardstick J.

<math>J = \frac{P_{0-14} - P_{50+}}{P_{15-49}}</math>

P_0-14: Population at the age of 0 to including 14 years
P_15-49: Population at the age of 15 to including 49 years
P₅₀₊: Population at the age of 50 years and older

For the computation of J thereby both absolute population numbers and population portions can be used.

Billeter sets the part of the population (P not reproducing yet_0-14) and/or. the part any longer not reproducing (P₅₀₊) in relation to the reproductionable population (P_15-49). Thus the status of a population is to be represented regarding his demographic development possibilities.

Range of values

The value of J can take thereby very different values, dependent on the age structure of a population.

positive values of J

J takes positive values, if in a population the portion of the young people is larger than the portion over 50jaehrigen. Thus point for example the majority of the countries in and high values up, there here with higher Birth rate and lower the number of the children and young person the number of the old persons exceeds clearly.
After Billeter such societies have a high degree at demographic development possibility, are thus strongly growing populations.

J equal 0

This case arises, if the number the number corresponds under 15jaehrigen to the number over 50jaehrigen. Such a relationship was in Europe about end that years.

negative values of J

J takes negative values, if in a population the portion is larger over 50jaehrigen than the portion of the children. In the western industrialized countries the values of J are clearly below 0. Here the birth rates are under that Reproduction level. At the same time rising Lebenserwartungenen provides for an increasing aging of the societies.
That is related to the demographic development possibility shrinking populations.