A sample concretely represents * n* experiments in which the same quantity is measured. For example, if * X* represents the height of an individual and * n* individuals are measured,
X
i
{\displaystyle X_{i}}
will be the height of the * i* -th individual. Note that a sample of random variables (. a set of measurable functions) must not be confused with the realizations of these variables (which are the values that these random variables take, formally called random variates ). In other words,
X
i
{\displaystyle X_{i}}
is a function representing the measurement at the i-th experiment and
x
i
=
X
i
(
ω
)
{\displaystyle x_{i}=X_{i}(\omega )}
is the value actually obtained when making the measurement.