A set (aggregate) of any elements (people, objects, events) related to each other logically (having common attributes or traits) but non-identical from the point of view of the studied feature. The general population includes all the items being studied, for which general conclusions are formulated. In the case when the elements of the general community are subjected to survey (examination) due to one feature, then this group is called one-dimensional (single-feature). The collectivity is called multidimensional (multi-feature) if many features are considered in the study.

• Interval of sampling
• Unit under observation
• Quota sampling
• Absolute numbers
• Relative numbers
• Simple random sampling
• Random sampling
• Minimal sample size
• Sampling scheme
• Snowball selection