Population and Sample Means
The mean of a population is denoted μ, known as the population mean. The sample mean makes a good estimator of the population mean, as its expected value is equal to the population mean. The sample mean of a population is a random variable, not a constant, and consequently it will have its own distribution. For a random sample of n observations from a normally distributed population, the sample mean distribution is
Often, since the population variance is an unknown parameter, it is estimated by the mean sum of squares, which changes the distribution of the sample mean from a normal distribution to a Student's t distribution with n − 1 degrees of freedom.
Read more about this topic: Mean
Famous quotes containing the words population, sample and/or means:
“I think that cars today are almost the exact equivalent of the great Gothic cathedrals: I mean the supreme creation of an era, conceived with passion by unknown artists, and consumed in image if not in usage by a whole population which appropriates them as a purely magical object.”
—Roland Barthes (1915–1980)
“As a rule they will refuse even to sample a foreign dish, they regard such things as garlic and olive oil with disgust, life is unliveable to them unless they have tea and puddings.”
—George Orwell (1903–1950)
“... in any war a victory means another war, and yet another, until some day inevitably the tides turn, and the victor is the vanquished, and the circle reverses itself, but remains nevertheless a circle.”
—Pearl S. Buck (1892–1973)