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Systematic random sample
| Glossary of Statistical Terms |
A systematic sample starting at a random point in the listing of units in the of frame, instead of starting at the first unit. systematic random sampling is better than systematic sampling, but typically not as good as simple random sampling.
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Systematic, английский
Common to all businesses.
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Selection bias, английский
- A systematic tendency for a sampling procedure to include and/or exclude units of a certain type. for example, in a quota sample, unconscious prejudices or predilections on the part of the interviewer can result in selection bias. selection bias is a potential problem whenever a human has latitude in selecting individual units for the sample; it tends to be eliminated by probability sampling schemes in which the interviewer is told exactly whom to contact (with no room for individual choice).
- A systematic difference between a target population and the sample of data. for example, data mining on customer complaint databases has a selection bias in that the data only capture customers who were motivated and able to contact the manufacturer about their complaint and does not capture complaints or customers who were not motivated nor able. self organizing map (som) a self organizing map is a form of kohonen network that arranges its clusters in a (usually) two-dimensional grid so that the codebook vectors (the cluster centers) that are close to each other on the grid are also close in the k-dimensional feature space. the converse is not necessarily true, as codebook vectors that are close in feature-space might not be close on the grid. the map is similar in concept to the maps produced by descriptive techniques such as multi-dimensional scaling (mds) self-stabilization a property of neural networks (e.g., art models). as a network trains itself on a finite number of cases, the various weights should gradually stabilize. see also: art, ftp:://ftp.sas.com/pub/neural/faq2.html, http://www.wi.leidenuniv.nl/art/.
Systematic sample, английский
A systematic sample from a frame of units is one drawn by listing the units and selecting every kth element of the list. for example, if there are n units in the frame, and we want a sample of size n/10, we would take every tenth unit: the first unit, the eleventh unit, the 21st unit, etc. systematic samples are not random samples, but they often behave essentially as if they were random, if the order in which the units appears in the list is haphazard. systematic samples are a special case of cluster samples.
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