Symbol

Meanings

f

Number of children each person has

NC_t

The number of the births in t^th society period

P_t

The total population in the t^th society period under basic scenario

Q_y

The total population in the y^th society period under earlier childbearing scenario

L

Each individual lives in the society for L periods.

d

Each individual has the child at d periods of his/her life under basic scenario

s

Each individual has the child at s periods of his/her life under earlier childbearing scenario