Six Sigma and Design of Experiments (DOE)

DOE helps to access through the vast amount of dataThe sequence of the experiment, which runs randomly,
collected as part of the Six Sigma projectwill allow all factors to affect all runs of the experiment.
implementation process and in designing experimentsThe drawback of a non-random run is the systematic
that are required to reduce variations and improveeffect the external factors may have on the
efficiency.experiment. Replication can help provide greater
What is DOE?amounts of data and greater value to the results.
Design of experiments is a formal statistical tool thatSuccessfully completed experiments will bring out the
helps to ensure that the testing phase of the projecteffect and the change in levels has on the responses.
produces data that would be beneficial for furtherThis helps to understand the best solution for the
improvements to the process. The aim is to maximizeprocess improvement and reduction in variation.
return on investment.Benefits of DOE
It is a systematic method to understand the cause andDOE helps to analyze the data to achieve quantifiable
effect relationship among the different factors thatresults to undertake experiments and make changes
affect the process and the variable results achievedto the processes to achieve the Six Sigma level. If Six
thereby. It even brings out the actual existence of anySigma concepts and methodologies are not
relation in the cause and effect. Using the advancedimplemented, precisely the expected results would not
statistical tools, it enables to understand the variationsbe achieved and it will hit the bottom line results of the
and to control them.organization adversely.
This helps to improve the predictability of the businessBeing a systematic way to approach the experiments
processes.to be undertaken, Six Sigma professionals can ensure
DOE is based upon factors, levels and responses. Athe best suited tests, which are conducted and which
factor in this case is an independent variable, which isin turn lead to achieve the expected improvements. As
given varied values with the purpose to achieve variedthe aim to set up processes is to achieve the same
results. The level is the state defined for that factor.quality of the products and services, the variations
The state varies and will bring out varied results. Thesehave to be identified and eliminated.
results are the responses achieved from theDOE helps to understand the root causes of variations.
experiment at different levels. The results achievedBeing well-equipped with the data on variations, Six
can be numerical or discrete values.Sigma professionals can work towards elimination of
In other words, Six Sigma professionals can selectsuch variations. This ensures the success of the Six
those experiment designs which are best suited toSigma implementation.
achieve the desired results from such experimentation.Design of experiments is thus an integral part of the
When selecting the factors and the state forSix Sigma implementation, irrespective of any specific
experiment, those factors that will generate pertinentindustry.
data relative to the expected results will be selected.