chapter  1
6 Pages

Introduction to Sampling

Persons engaged in the management or utilization of forest resources are required to make decisions of many kinds regarding those resources. For example, timber managers must decide whether a certain slash pine plantation, damaged by ice, should be clear-cut and a new stand established or if the plantation should be permitted to recover as much as possible and carried to its normal rotation age; or wood procurement foresters must decide what they would be willing to pay for the timber on a certain tract of land; or state wildlife managers must decide whether or not the deer herd in a certain portion of the state is large enough to survive hunting pressure during a specified open season. If such decisions are to be made in an intelligent manner, they must be made on the basis of sound information about the resource in question. Much of this information can only be obtained by assessment or inventory of the resource. Preferably such assessments or inventories would be based on

all

the individual organisms or items involved, but only rarely is this possible. The costs, in terms of money and time, for complete inventories are almost always excessive. Consequently, the decisions have to be made using knowledge based on an evaluation of only a small portion of the whole. When this occurs,

sampling

is involved. Often many sampling options are available. The validity and strength of the results vary from

option to option. In addition, the costs, in terms of money and time, also vary. It is desirable, therefore, that the decision maker have an idea of the nature of the available procedures, their strengths and weaknesses, and their relative costs. The procedure used in any specific case should be one that yields the needed information, at the desired level of precision, at the lowest cost in money and time. It should be recognized at the outset that inventories are not, by themselves, productive. They produce income only for those doing the work. Consequently, it is rational to use procedures that produce the greatest benefit: cost ratios. This book is written to provide background for land managers so that they can apply this philosophy to their inventory operations.