To a statistician a survey means gathering information from a population. The use of the word population betrays the origin of statistical surveys in understanding people. Early in the development of statistics it was realised that it was often not necessary to collect information on everyone (a census) but just looking at a subset of the population could give reasonable accuracy if chosen properly. This is a sample survey, but the aim is still to obtain an overview of the whole population. The statistician’s expertise covers the methods of choosing the sample, a blend of theory and practical experience.
The principles of surveys and sampling developed for people can be applied in many other contexts, even though they are not always called surveys. For example, in quality management it is not efficient to inspect every single product coming off a production line, but it may be possible to inspect a small subset and on that basis decide whether the production line is operating satisfactorily. Accountants use sampling of transactions when conducting an audit – checking a sample may provide sufficient confidence that the vast majority of transactions are accurate and hence the financial statements based upon them are a true and fair view.