| 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
|
