Unit of observation in the context of Data

Level of analysis is used in the social sciences to point to the location, size, or scale of a research target. It is distinct from unit of observation in that the former refers to a more or less integrated set of relationships while the latter refers to the distinct unit from which data have been or will be gathered. Together, the unit of observation and the level of analysis help define the population of a research enterprise.

An Archimedean point (Latin: Punctum Archimedis) is a hypothetical viewpoint from which certain objective truths can perfectly be perceived (also known as a God's-eye view) or a reliable starting point from which one may reason. In other words, a view from an Archimedean point describes the ideal of removing oneself from the object of study so that one can see it in relation to all other things while remaining independent of them.

For example, the philosopher John Rawls uses the heuristic device of the original position in an attempt to remove the particular biases of individual agents to demonstrate how rational beings might arrive at an objective formulation of justice.

In statistics, missing data, or missing values, occur when no data value is stored for the variable in an observation. Missing data are a common occurrence and can have a significant effect on the conclusions that can be drawn from the data.

Missing data can occur because of nonresponse: no information is provided for one or more items or for a whole unit ("subject"). Some items are more likely to generate a nonresponse than others: for example items about private subjects such as income. Attrition is a type of missingness that can occur in longitudinal studies—for instance studying development where a measurement is repeated after a certain period of time. Missingness occurs when participants drop out before the test ends and one or more measurements are missing.