DESIGN OF EXPERIMENT USING TAGUCHI METHOD

'Design of Experiment (DOE) is a method of simultaneously investigating the effects of multiple variables on an output variable or response'. It is a key tool in the Six Sigma methodology because it effectively explores the cause and effect relationship between numerous process variables and the output.

Worldwide there are 3 approaches followed for Design of Experiments.

	First approach was conceived and developed by Sir Ronald A. Fisher in the 1920s and 1930s to arrive at the best combination of inputs in agriculture [meaning soil, water, sunshine etc].
	The other approach is of Design of Experiments using Shainin Method. This method was developed by Dorian Shainin, and is similarly used in solving real life complicated quality issues.
	The third and the most popular approach for Design of Experiment today is using the Taguchi Method. Taguchi methods, developed by Dr. Genichi Taguchi, refer to techniques of quality engineering that embody both statistical process control (SPC) and new quality related management techniques.

SSA has a tie up with Nutek Inc, USA, for Consulting and Training on the Design of Experiment using 'Taguchi Method'.
The 'Taguchi Method for Design of Experiments' was developed by Taguchi in isolation from the school of R. A. Fisher; only coming into direct contact in 1954. His framework for design of experiments added enormous value to the Traditional Design of Experiments, as he made a number of innovations to the same.

The entire concept of Taguchi Method can be described in two basic ideas:

	"Quality should be measured by the deviation from a specified target value, rather than by conformance to preset tolerance limits
	Quality cannot be ensured through inspection and rework, but must be built in through the appropriate design of the process and product"

Taguchi sought to understand the influence that parameters had on variation, not just on the mean. He contested that conventional sampling is inadequate for analytic studies as there is no way of obtaining a random sample of future conditions. In conventional design of experiments, variation between experimental replications is something that the experimenter would like to eliminate whereas, in Taguchi's thinking, it is a central object of investigation. 'Taguchi's innovation was to replicate each experiment by means of an outer array, itself an orthogonal array that seeks deliberately to emulate the sources of variation that a product would encounter in reality.

'Taguchi introduced many methods for analysing experimental results including novel applications of the analysis of variance and minute analysis. He has made seminal and valuable methodological innovations in statistics and engineering, within the Shewhart-Deming tradition.' His emphasis on 'loss to society'; techniques for investigating variation in experiments and his overall strategy of system, parameter and tolerance design have massively contributed to improving manufactured quality worldwide.

Following are some comments that describe the 'Design of Experiments using Taguchi Method'

"Traditionally, engineers tend to change only one variable of an experiment at a time. The strength of the Taguchi technique is that the engineer can change many variables at the same time and still retain control of the experiment."
- Steven Ashley (Mechanical Engineering, July 1992)

"Taguchi's . . . method separates factors into three categories: control factors, which are important in reducing variation; adjustment factors, which are used to set output at a desired target; and cost-adjustment factors, which, though unimportant for determining variation of output levels, are useful for improving a product's cost effectiveness."
- Steven Ashley (Mechanical Engineering, July 1992)

"This approach leads to an economy of experimentation that speeds the entire process."
- Madhav Phadke (Mechanical Engineering, July 1992