The terms demographics and population statistics are borrowed by astronomy, used regarding statistical studies of large sets of some type of object regarding their traits, to theorize, e.g., about their creation and evolution. For example, the phrase exoplanet demographics is used for studies of exoplanets that gain information from the counts of those exoplanets with specific characteristics. The term may be qualified by an indication of the selection criteria, e.g., Milky-Way demographics, which might be used regarding some type of object (e.g., stars) specifically within the Milky Way. The study must take into account biases inherent in observation, e.g., which planets and stars are in a position to be found, so means of adjusting for these biases are of interest.
When objects are discovered forming some new class, initially there may be too few observed to lend any statistical significance to counts of subsets with various characteristics, but as the discovery of more such objects takes place, a point may be reached when it is said that demographics of the object type is of use.
The term demographics is borrowed from the statistical study of human populations, such as through data from a country's census, and the term has also been used regarding astronomy in this more-original sense; the phrase demographics of astronomy has been used for population statistics of people working in the field.