Stratified sample
A sample which is broken up into several samples of smaller sizes by certain distinguishing marks (characteristics). Let each element of some sample of size possess one and only one of
possible marks. Then the original sample can be broken into
samples of sizes
, respectively
:
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where the -th sample
contains only those elements of the original sample which have the mark
. As a result of this decomposition, the original sample becomes stratified into
strata
,
, where the
-th stratum contains information about the
-th mark. This notion gives rise, for example, to realizations of the
-component of a two-dimensional random variable
whose second component
has a discrete distribution.
References
[1] | S.S. Wilks, "Mathematical statistics" , Wiley (1962) |
Comments
References
[a1] | W.G. Cochran, "Sampling techniques" , Wiley (1977) |
Stratified sample. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Stratified_sample&oldid=49450