分层抽样法在实验室废液量统计中的应用

实验室废液由于受实验室性质和科研课题数量的影响,其排放源分散,废液排放周期不定,排放水量也无规律性;因此要对一个城市和一定区域实验室的废液排放量进行准确统计监管非常困难.本文采用分层抽样中的比率估计法SRE对某城市实验室废液进行了统计.统计结果显示,该城市科研实验室废液排放总量为107.8 T,统计误差为10.04 T.实验室间的差异以及调查统计的准确性是造成误差的主要原因.该方法用于实验室废液的统计能够反映实际的废液排放情况,适合于环保管理部门用来对实验室废液进行监管.

Application of stratified ratio estimation in statistics of lab sewage quantity

This paper aims to introduce the authors' method on applying SRE(stratified ratio estimation) for the statistics of the lab sewage quantity.As is known,laboratory sewage is usually discharged irregularly and in turn its quantity is irregular too.Therefore,it is very difficult to estimate and monitor the discharge amount accurately.So far,there seems no available method to solve this problem.It is just starting from this actual need,the present authors have tried stratified sampling method in accordance with the different conditions of different strata or levels of laboratories.In doing so,we have divided laboratories into some strata,leaving some differences between units in the same stratum but trying to find a certain difference between each strata in order to reduce the sample errors.That is to say,first of all,try to choose certain typical scientific establishments to set up collecting facilities to make accurate recordings of the laboratory sewage discharge.Then,compare the scientific establishments with some other laboratories available to get the ratio estimate so as to estimate the whole discharge of the target laboratories(or those of a city).At the same time,error estimation can be done for analysis.The result shows that: the total amount of laboratory sewage in scientific establishments would be about 107.8 ton,with the statistical errors being about 10.04 ton.The differences between laboratories and the veracity of investigation are the main cause of statistical errors.The actual results of using SRE can reflect the actual discharge amount quite well.Therefore,the method is also suitable for the Environmental Protection departments to monitor the sewage discharge of different laboratories.