ABSTRACT
Although practical considerations place an upper limit on the number of measurements we are likely to make, in principle there is no limit to the number. This situation is described by saying that the size of the population is infinite. The actual number of measurements made is called the sample, and is clearly of finite size, N. What we are trying to do in experiments is to make a good estimate of the properties of the population, while only making a finite number of readings. At first sight this may appear an impossible dream since you do not need to be much of a mathematician to realize that 10 or 20, say, is a long way short of infinity. Fortunately, it turns out that we can indeed get a reasonable understanding of the population from a sample of such a size. Clearly it will not be perfect knowledge, but scientists can do wonders with incomplete information!
