Sampling Finite Populations
This chapter considers the basic ideas of sampling with special reference to the use of sampling in experiments. The purpose of experiments is to make inferences, as unambiguously as possible, about the effects of treatments applied to experimental units. The units are taken as representative of the population of units to which the treatments may in the future be applied. The objectives of sample surveys are to allow inferences to be made from a sample about the whole, but always finite, population from which it was drawn. The chapter discusses some of the standard modifications of sampling procedures. To illustrate the use of simple random sampling, it also discusses the sampling, for the purpose of leaf area measurement, of leaves from an experimental plot. A certain number of plants may be sampled, perhaps using stratified random sampling with the rows of plants forming the strata, and then a random sample of leaves chosen to represent each sampled plant.