In almost all the fields of inquiry, experiments are
carried out in order to discover some findings about
the processes or systems. An experiment can be
defined as a test or series of tests in which purposeful
changes were made to the input factors of a process
or a system, so that the reason for the changes were
observed and identified. The design concept of the
experiments has been in use since Fisher's work in
agricultural experimentation. Fisher successfully
designed experiments to determine the optimum
treatments for the land to achieve a maximum yield
[15].
The first step in designing any experiment is
recognizing the problem. This is followed by the
determination of the effective factors with their levels
and specifying a response variable. Then, based on
the objectives, one must select a suitable
experimental design and carry out the experiments
accordingly. The obtained data would be studied
using the analysis of variance (ANOVA) method,
leading to the determination of the factors with a
significant effect on a response variable. Finally, a
model can be worked out which represents the
response variable as a function of the already
determined significant factors. The choice of the
experimental design depends on the type of problem,
the number of factors, as well as their levels [16].