When studying the properties of an objectThe characteristic of not all the units of the general population is determined, but only of some of its parts. This makes it possible, by performing a selective observation of the selected region, to characterize quite adequately all the objects as a whole for some particular distinguished feature or property.
In order for the selected objects to be able to represent all the units under study with sufficient probability, the work must be organized in a certain way.
There are several traditional methods,allowing to extend selective observation to the whole population, the main ones are the following: the method of coefficients and direct recalculation. The first option is used in cases where it is necessary to verify or refine data obtained as a result of continuous observation. In the second case, the product of the mean value of the test feature is determined for the whole volume of the general population. In this case, it is necessary to take into account the fact that not all factors allow full use of a point estimate in the dissemination of results obtained for sampling the general population. Therefore, in practice, an interval estimation has been widely used, with the help of which it is possible to take into account the size of the marginal error of a part of the population and to calculate it for the average, and, if necessary, for the fraction of the trait.
When the research is not carried out on the wholeof the general population, but only on its part, errors of selective observation, which cause deviation of the received results from true values, inevitably arise. At the same time, there are two main reasons that can cause distortion of the final result:
The selective observation in statistics isfairly wide application. In this case, reliable information about the objects of research can be obtained, significantly saving money and reducing costs. The guarantee of the representativeness of the studies is the scientifically based selection of respondents for the study.
In practice, selective observation is most oftenIt is conducted on objects that have been selected in a random or regionalized way. In the first case, the same probability is provided that one or another unit will fall into the sample set. If the object of research, after receiving information about it, returns to the general population, then the random sample is called repeated. Otherwise, it is repetitive. The zoned sample is formed as a result of the dismemberment of the general population into a number of regions (groups), depending on the nature of the trait being studied. The use of suitable selection techniques allows for the presence of representatives from each group in the selected population.
If we talk about how a selective observation should be organized, then in this case it is necessary to observe the following conditions:
This will allow you, by minimizing the volume of ongoing research, to obtain reliable information on the issues you are interested in.
