Fractional Factorial



A fractional factorial algorithm chooses a subset of the full factorial combinations.

In Rezen the fractional factorial algorithm is only implemented as a three level algorithm, i.e. each uncertainty variable has a low, mid and high value (-1,0,+1).
The algorithm is implemented to give the engineer the option of building a hybrid design by including or excluding the Tornado, Plackett-Burman and Box-Behnken algorithms, i.e. it is implemented as a combination of other three level designs.

So, for example, with 5 uncertainty variables each having a low, mid and high value, if we include the Tornado algorithm then 2*nvariables+1 or 2*5+1=11 simulation decks will be created. If we add Plackett-Burman then an additional 10 decks will be created (each of which has a different combination of uncertainty variable values). We could also include Box-Behnken which, depending on the number of blocks we use, will add between 40 and 80 more simulation decks.