Milky Way galaxy in the context of "Population mean"

In statistics, a population is a set of similar items or events which is of interest for some question or experiment. A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypothetical and potentially infinite group of objects conceived as a generalization from experience (e.g. the set of all possible hands in a game of poker). A population with finitely many values ${\displaystyle N}$ in the support of the population distribution is a finite population with population size ${\displaystyle N}$. A population with infinitely many values in the support is called infinite population.

A common aim of statistical analysis is to produce information about some chosen population.In statistical inference, a subset of the population (a statistical sample) is chosen to represent the population in a statistical analysis. Moreover, the statistical sample must be unbiased and accurately model the population. The ratio of the size of this statistical sample to the size of the population is called a sampling fraction. It is then possible to estimate the population parameters using the appropriate sample statistics.

RS Puppis (or RS Pup) is a Cepheid variable star around 6,000 ly away in the constellation of Puppis. It is one of the biggest and brightest known Cepheids in the Milky Way galaxy and has one of the longest periods for this class of star at 41.5 days.

Richard Brent Tully (born March 9, 1943) is a Canadian-born American astronomer at the Institute for Astronomy in Honolulu, Hawaii.

Born in Toronto, Ontario, and raised in Vancouver, British Columbia, Tully's specialty is the astrophysics of galaxies. With J. Richard Fisher, he proposed the Tully–Fisher relation, which shows that the luminosity of a galaxy and the orbital velocities of its stars are correlated. This relation can be used to determine the distances of galaxies and, by inference, the size and age of the universe. His books The Nearby Galaxies Atlas & Catalog published in 1988 give the 3D locations for 2,400 galaxies within 130 million light years of Earth. A particularly remarkable discovery was that our Milky Way galaxy lies adjacent a vast underdense region that Tully called the Local Void. A more extended compilation of 30,000 galaxies within a cube of diameter 700 million light years centered on Earth can be visually navigated with the planetarium computer software Starry Night Pro, where the data is called the Tully Database.