Caughley Graeme
Ecology. 1967 Sep;48(5):834-839. doi: 10.2307/1933741.
Lotka's equations relating the parameters of populations with no seasonal trend in birth rates and Fisher's formula for "reproductive value" are modified to describe populations with restricted annual seasons of birth. The parameters "net reproductive rate" and "mean generation length" provide statistics and dubious utility for populations with overlapping generations. New definitions of birth rate and death rate are proposed whereby the relationships between the crude, finite and exponential rates are simplified. The use of these parameters is illustrated by statistics calculated for a population of sheep.
洛特卡方程（用于描述出生率无季节性趋势的种群参数）和费希尔的“生殖价值”公式被修改，以描述出生季节受年度限制的种群。“净生殖率”和“平均世代长度”这两个参数对于具有重叠世代的种群而言，所提供的统计数据效用存疑。本文提出了出生率和死亡率的新定义，借此简化了粗出生率、有限出生率和指数出生率之间的关系。通过对一群绵羊计算得出的统计数据，说明了这些参数的用途。
