As a result of doing less experiments, the amount of information that is generated from a fractional factorial experiment is less than from a full factorial experiment, but the practical difference may not be great.
22.
In statistics, a full "'factorial experiment "'is an experiment whose design consists of two or more factors, each with discrete possible values or " levels ", and whose experimental units take on all possible combinations of these levels across all such factors.
23.
This experiment is an example of a 2 2 ( or 2x2 ) factorial experiment, so named because it considers two levels ( the base ) for each of two factors ( the power or superscript ), or # levels # factors, producing 2 2 = 4 factorial points.
24.
In addition, other aspects were varied in a full factorial experiment with four between-subject binary factors : 1 ) either pairs or triads of letters; 2 ) encircling the preferred letter or crossing out the less preferred; 3 ) QXYZ included or excluded; 4 ) own-name letters listed first or last.
25.
For more than two factors, a 2 k factorial experiment can be usually recursively designed from a 2 k-1 factorial experiment by replicating the 2 k-1 experiment, assigning the first replicate to the first ( or low ) level of the new factor, and the second replicate to the second ( or high ) level.
26.
For more than two factors, a 2 k factorial experiment can be usually recursively designed from a 2 k-1 factorial experiment by replicating the 2 k-1 experiment, assigning the first replicate to the first ( or low ) level of the new factor, and the second replicate to the second ( or high ) level.
27.
For example, the 2 ^ { 5-2 } can be generated by using the full factorial experiment involving three factors ( say A, B, and C ) and then adding two extra factors D and E generated by D = A * B and E = A * C, where the low level of a factor is given by-1 and the high level of a factor is given by + 1.
28.
Suppose an engineer wishes to study the total power used by each of two different motors, A and B, running at each of two different speeds, 2000 or 3000 RPM . The factorial experiment would consist of four experimental units : motor A at 2000 RPM, motor B at 2000 RPM, motor A at 3000 RPM, and motor B at 3000 RPM . Each combination of a single level selected from every factor is present once.
