Sampling Frame
In the most straightforward case, such as the sentencing of a batch of material from production (acceptance sampling by lots), it is possible to identify and measure every single item in the population and to include any one of them in our sample. However, in the more general case this is not possible. There is no way to identify all rats in the set of all rats. Where voting is not compulsory, there is no way to identify which people will actually vote at a forthcoming election (in advance of the election). These imprecise populations are not amenable to sampling in any of the ways below and to which we could apply statistical theory.
As a remedy, we seek a sampling frame which has the property that we can identify every single element and include any in our sample. The most straightforward type of frame is a list of elements of the population (preferably the entire population) with appropriate contact information. For example, in an opinion poll, possible sampling frames include an electoral register and a telephone directory.
Read more about this topic: Sampling (statistics)
Famous quotes containing the word frame:
“Human life itself may be almost pure chaos, but the work of the artistthe only thing hes good foris to take these handfuls of confusion and disparate things, things that seem to be irreconcilable, and put them together in a frame to give them some kind of shape and meaning. Even if its only his view of a meaning. Thats what hes forto give his view of life.”
—Katherine Anne Porter (18901980)