Good experimental design is important in many studies of analytical
and other chemical processes. Complete factorial designs, which study
all the factors (experimental variables) affecting the system response,
using at least two levels (values) for each factor, can give rise to an
unacceptably large number of trial experiments. This is because even
apparently simple processes may be affected by a large number of
factors. Moreover these factors may affect the system response
interactively, i.e. the effect of one factor may depend on the levels of
others. Any interactions must also be distinguished from random
measurement errors. So it is more common to use partial factorial
designs in which some information, especially about interactions,may
be sacrificed in the interests of a manageable number of experiments.