(Feedback from Statistics Estonia; 5 October, 2017)
There can be a misunderstanding in the explanation to Figure 14. Variable (see GSIM 1.1 page 80):
- ... a Unit Type defining a Population is associated with a characteristic. The association of Unit Type and a Concept playing the role of a characteristic is called a Variable.
- In the context of statistical activity (survey), other unit types can exist, not defining a population, but also used for description of variables, combining concept with unit type. May be it should be explained in more detail. For example:
- Statistical activity – Vital events. Births
- Population – Births by women who are permanent residents of Estonia n Unit – Birth
- Frame – Births in the given year registered in the Population Register
- In addition to variables: live births, stillbirths, birth order, number of deliveries and multiple births, etc. characterising unit type Birth, there are other units and unit types used in this statistical activity, but not determining the population (births) – gender of person, age of mother (person), duration of marriage, etc.
After the studying UML Diagrams (Annex C) page 117 it becomes clear, that in the context of survey several unit types can be used for definition of variables, but not all of them are related to population.