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Center point

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Center point

Center points are half way between all the high and low values in the experiment so they are in the center.

Why are Center points used?

  1. To determine if a relation is linear or not
  2. Measure the stability and the variation during the experiment
  3. To increase the statistical power of a design
Therefor the center points should be at the begin, end and evenly distributed throughout the experiment. So do not randomize the center points!

Examples

CCD2

Tests Factors
AB
1
(Center point)
00
2-1-1
31-1
4
(Center point)
00
5-11
611
7
(Center point)
00
8-1.4140
91.4140
10
(Center point)
00
110-1.414
1201.414
13
(Center point)
00
Graphical image of the CCD2 array

More images of designs with center points



Center point in a Central Composite design


Center point in a Box-Behnken design
Blue
Center point

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