ESTIMATING THE SIZE OF POPULATION FROM A SINGLE SAMPLE

估计个体群体的大小通常需要 无论是全面普查还是多次抽样--一次捕获-- 重新捕获人口普查。 然而，对许多人口来说， 这是不可能的，两个阶段的办法可能不能令人满意。 标记 可能是不可能的，安装单独的捕获工作的成本可能 如果两个样本中的个体较大，则可能难以匹配，或者 封闭性假设（之间无增删） 捕获）可能是有疑问的。 Laska，Meisner and Siegel（1989）和Laska and Meisner（1992） 开发了两种方法，只需要一个单一的样本，克服了 许多问题。 在第一种方法中，期望估计 从事特定活动的人数， 一段特定的时间，例如，接受治疗的人 1992年的任何一家精神病院 在调查中， 获得关于个人最后一次与 活动，例如，对于在调查期间前来服务的患者， 周，自他们上次来服务以来的周数是 确定。 在第二种称为植物捕获方法的方法中， 估计人口在一个单一的点的大小， 时间 种植已知数量的个体，并且（通常） 执行重新捕获阶段。 这两种方法都可以估计 量p的值，类似于捕获的概率，反过来， 可以估计人口规模。 我们建议扩展和改进单捕获方法。 这包括 处理多个研究中心、亚群、测试的统计方法 减少样本量，合并两个单样本 方法. 通过协商，这些建议将具体适用于 三个目标心理健康人群：（一）无家可归者人数， （二）在一个地区的精神病患者无家可归;（二）不重复的数量 一年内在精神卫生管辖区接受服务的患者;以及 (iii)使用普通保健设施的病人比例 患有精神疾病的人。 单样本方法可能适用 估计许多其他心理健康目标群体的规模，例如， 例如，在一个实施例中，居住在社区的长期精神病患者，以及 患有精神病的化学品滥用者

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.