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The Plackett-Burman design is a type of Resolution III experimental design that is often used as a screening design. The number of runs in a Plackett-Burman designs is a multiple of 4, thus avoiding the limitations of factorial and fractional factorial designs where the number of runs is 2k.
The generating vectors for selected Plackett-Burman designs are below:
| n=8 |
(+ + + - + - -) |
| n=12 |
(+ + - + + + - - - + -) |
| n=16 |
(+ + + + - + - + + - - + - - -) |
| n=20 |
(+ + - - + + + + - + - + - - - - + + -) |
| n=24 |
(+ + + + + - + - + + - - + + - - + - + - - - -) |
| n=36 |
(- + - + + + - - - + + + + + - + + + - - + - - - - + - + - + + -- + -) |
The generating vectors have ‘n-1’ rows. The last row of a Plackett-Burman design contains only ‘-‘ values.
The design will have 'n-1' columns and a factor will be allocated to each column:
- put the generating vector into the first column (column ‘A’)
- copy the last value from column A into the first row of column B
- slide the rest of the values from A below that value
- copy the last value from column B into the first row of column C
- slide the rest of the values from column B below that value
- continue until all the columns have been populated
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