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Factorial designs allow the effects of a factor to be estimated at several levels of the other factors, yielding conclusions that are valid over a range of experimental conditions. The main disadvantage of the full factorial design is its sample size requirement, which grows exponentially with the number of factors or inputs considered. [6]
In the design of experiments, a between-group design is an experiment that has two or more groups of subjects each being tested by a different testing factor simultaneously. This design is usually used in place of, or in some cases in conjunction with, the within-subject design , which applies the same variations of conditions to each subject ...
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Example of direct replication and conceptual replication There are two main types of replication in statistics. First, there is a type called “exact replication” (also called "direct replication"), which involves repeating the study as closely as possible to the original to see whether the original results can be precisely reproduced. [ 3 ]
Montgomery [3] gives the following example of a fractional factorial experiment. An engineer performed an experiment to increase the filtration rate (output) of a process to produce a chemical, and to reduce the amount of formaldehyde used in the process. The full factorial experiment is described in the Wikipedia page Factorial experiment ...
For example, the X 1 coefficient might change depending on whether or not an X 2 term was included in the model. This is not the case when the design is orthogonal, as is a 2 3 full factorial design. For orthogonal designs, the estimates for the previously included terms do not change as additional terms are added.
This idea applies to fractions of "classical" designs, that is, (or "symmetric") factorial designs in which the number of levels, , of each of the factors is a prime or the power of a prime. A fractional factorial design is regular if it is the solution set of a system of one or more equations of the form
Plackett–Burman designs are experimental designs presented in 1946 by Robin L. Plackett and J. P. Burman while working in the British Ministry of Supply. [1] Their goal was to find experimental designs for investigating the dependence of some measured quantity on a number of independent variables (factors), each taking L levels, in such a way as to minimize the variance of the estimates of ...