The mathematics of a population composed of k stationary strata each recruited from the stratum below and supported at the lowest level by a uniform annual number of entrants
成果类型：
Article
署名作者：
Seal, HL
刊物名称：
BIOMETRIKA
ISSN/ISSBN：
0006-3444
DOI：
10.2307/2332300
发表日期：
1945
页码：
226230
关键词：
摘要：
A population is considered subject to specified stochastic decremental forces operating at each age and supported by an annual number of entrants distributed between certain limits by a known frequency law. It is assumed that the population has existed for at least a certain number of yrs. The individuals of the now stationary population are divided into a certain number of strata. The numbers in each of the strata are determined by a chance force operating on the individuals of each stratum, with an intensity which depends only upon the length of time the individual has spent in that stratum; if selected, the individual goes into the next higher stratum. The total decremental and selective forces acting at each age and duration are respectively invariant with time. This article develops expression, under certain assumptions, for (a) The expected number of entrants at any given moment into a certain stratum at a certain age. (b) The expected total number of individuals in a certain stratum at any instant of time. After these have been found, special cases are considered.