Sample mean

The arithmetic average of the observations in a finite sample, calculated by adding their values and dividing by the number of observations.

Arithmetic mean: A measure of central tendency equal to the sum of values divided by their count. The sample mean is the arithmetic mean computed from sample observations.
Observation (statistics): A recorded value or measurement included in a statistical dataset. Each observation supplies one of the values averaged in a sample mean.
Point estimation: The use of sample data to estimate an unknown population parameter with a single value. The sample mean is a point estimate of a population mean.
Median: The middle value of an ordered dataset, or the midpoint of its two central values. Unlike the sample mean, the sample median is resistant to extreme observations.
Weighted arithmetic mean: An average in which values contribute according to assigned weights. Unequally weighted observations require a different formula from the ordinary sample mean.
Sample (statistics): A subset of units or observations selected from a population for statistical analysis. A sample mean summarizes the observed values in this subset.
Unbiased estimator: An estimator whose expected value equals the parameter it estimates. Under random sampling, the sample mean is unbiased for the population mean when that mean exists.
Mode (statistics): The most frequently occurring value in a dataset or probability distribution. The mode summarizes frequency rather than balancing all sample values by their magnitudes.
Linearity of expectation: The expected value of a sum equals the sum of the expected values, without requiring independence. It lets the expected sample mean be derived by averaging the observations' expectations.
Population mean: The arithmetic average of every value in a defined population. It is the population quantity that a sample mean often estimates.

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