ESTIMATING THE SIZE OF POPULATION FROM A SINGLE SAMPLE

估计个体的数量通常需要 要么是全面普查，要么是多次抽样--捕获-- 重新夺回人口普查。然而，对于许多人口来说，全面的人口普查可能是 这是不可能的，分两个阶段的方法可能不能令人满意。标记 可能是不可能的，安装单独捕获努力的成本可能 体型较大时，两个样本中的个体可能很难匹配，或者 关闭的假设(之间没有添加和删除 捕获)可能有问题。 Laska，Meisner和Siegel(1989)和Laska and Meisner(1992) 开发了两种方法，只需要一个样本，就可以克服 很多问题。在第一种方法中，希望估计 从事某一特定活动的不同人数 一段特定的时间，例如，接受治疗的个人 任何一个州的精神卫生机构在1992年。在一次调查中， 获得有关个人最后一次与 活动，例如，针对在调查期间前来服务的患者 一周，他们最后一次来服务的周数是 已经确定了。在第二种方法中，称为植物捕获法，它 是为了估计某一时刻的人口数量。 时间到了。已知数量的个体被种植，(通常) 执行重新捕获阶段。这两种方法都支持估计 数量，p，类似于捕获的概率，这反过来， 启用对人口规模的估计。 我们建议扩展和改进单次捕获方法。这包括 处理多个站点、子群、测试的统计方法 减少样本大小，合并两个单一样本 方法：研究方法。通过协商，这些规定将具体适用于 三个心理健康目标人群：(1)无家可归者和 在某一地区无家可归的精神病患者；(Ii)未重复的人数 在一年内在精神健康司法管辖区接受服务的病人；以及 (3)使用普通保健设施的病人比例 有精神障碍的人。可能适用单一样本方法 估计许多其他心理健康目标群体的规模，例如， 例如，居住在社区的长期精神病患者，以及 精神病药物滥用者。

Estimating the size of a population of individuals usually requires either a full census or samples on multiple occasions - a capture- recapture census. However, for many populations a full census may be impossible, and the two-stage approach may be unsatisfactory. Marking may not be possible, the cost of mounting separate capture efforts may be large, matching individuals in the two samples may be difficult, or the assumption of closure (no additions and no deletions between captures) may be questionable. Laska, Meisner and Siegel (1989) and Laska and Meisner (1992) have developed two methods, that require only a single sample, that overcome many of the problems. In the first approach, it is desired to estimate the distinct number of persons who engage in a specific activity during a specified period of time, e.g., individuals who received treatment in any mental health facility in a state during 1992. During a survey, information is obtained as to when individuals were last associated with the activity, e.g., for patients who came for service during the survey week, the number of weeks since they last came for service is ascertained. In the second approach called the plant-capture method, it is desired to estimate the size of a population at a single point in time. A known number of individuals are planted, and the (usual) recapture phase is performed. Both of these methods enable estimation of quantity, p, analogous to the probability of capture, which, in turn, enables estimation of the population size. We propose to extend and refine single capture methods. This includes statistical approaches to handle multiple sites, subpopulations, tests of bias, reducing the sample size and combining the two single sample methods. Through consultations these will be specifically applied to three target mental health populations: (i) the number of homeless and the mentally ill homeless in an area; (ii) the unduplicated number of patients receiving service in a year in a mental health jurisdiction; and (iii) the proportion of patients utilizing a general health care facility who have psychiatric disorders. Single sample methods may be applicable to estimating the size of many other mental health target groups such as, e.g., the chronically mentally ill who reside in the community, and mentally ill chemical abusers.