n=(t~2c~2)/E~2这是我们森林调查规划工作者经常要使用的一个公式。也是大多数与抽样调查打交道的同志所熟悉的一个公式,计算必要的抽样数n这是抽样设计工作中的一个重要步骤。n不能过大以免调查工作付出过多的人力、物力、财力、时间方面的代价,n也不能过小以致于不能实现予先规定的精度与可靠性方面的要求,这等于完不成调查任务。 n = (t ~ 2c ~ 2) / E ~ 2 This is a formula often used by forest survey planners. It is also a formula familiar to most comrades who deal with sample surveys and calculates the necessary number of samples. N This is an important step in sample design. n It should not be too great for the investigation personnel to pay too much manpower, material resources, financial resources and time, nor can they be too small to achieve the prescribed accuracy and reliability requirements. This is tantamount to failing to complete the task of investigation.