Six Sigma

Six Sigma is a Rigorous and disciplined problem solving methodology that uses data and statistical analysis to measue and improve a company's operating performance by identifying and eliminating defects in manufacturing and service related processes.
In Statistical Parlence Six Sigma is commonly defined as 3.4 defects per million opportunities(DPMO) or 2 defects per billion opportunities.
Six sigma can be understood at three different levels.........
1. Metric-it is a scale or level of quality which defined not more than 3.4 defects per million opportunities(DPMO).rule of thumb is to consider atleast three opportunities for a physical part-one for the form,one for and one for function
2.Methodology-there are several structural problem solving roadmaps and tools like
DMAIC,DMAIV,DMADV,PIDOV etc.
DMIAC=define,measure,analyze,improve and control
DMAIV=define,measure,analyze,improve and verify
DMADV= define,measure,analyze,design and verify
PIDOV=plan,identify,design,optimize and validate
it is a business improvement methodology that focus on..............
a.understanding customer requirement
b.aligning key busines processes to achieve the requirements
c.rigorous data analysis to minimize variations
d.sustainable improvement to business processes
3.Management-Reduce variation and take customer focussed data driven decisions.like...
a.align business strategy
b.accelerate improved business results
c.govern to ensure that results are sustained
where sigma denotes standard deviation
6 sigma means six standard deviations between the process mean and the nearest specification limit.
From where does the name Six Sigma formulated?
Bill Smith a quality engineer at Motorola was entrusted the task of suggesting measures to improve the manufacturing process,bill smith coined the improvement mesurements as Six Sigma in 1986

what is 1.5 sigma shift?

six sigma really corresponds to a sigma value of 4.5.where does this 1.5 sigma difference come from?Motorola has determined through years of process and data collection,that processes vary and drift over time-what they call the long term dynamic mean variation.this variation typically falls between 1.4 and 1.6, average comes to be 1.5.
After the process have been improved using the six sigma DMAIC methodology,we calculate the process standard deviation and sigma value.they are considered to be short term value because the data only contains common cause variation and not the special cause variation
where as the long term data contains both types of variation.since short term data does not contain special cause variation,it will typically be of higher process capability than the long term data.this difference is 1.5 sigma shift
the reporting convention of six sigma requires the process capability to be reported in short term sigma.

Why six sigma is implemented?
1.Improve customer satisfaction
2.Increase profitability
3.Increase Productivity

why an organization uses six sigma?
1. improve customer satisfaction
2.Lower cost
3.Grow revenue
4.increase capacity
5.Increase capability
6.Reduce complexity
7.Lower cycle time
8.Minimize defects and error

six sigma action occurs at two level
1.Managerial level-it includes
a.people
b.technologies
c.project
d.schedule
e.details to be managed and co-ordinated
2.Technical level-
a.set proper management orientation

Statistical tools
1.Measure of centeral tendency
2.Regresion analysis
3.co-relation
4.sampling Distribution
5.Hypothesis
6.design of experiments and ANOVA
7.goodness of fit
8.Control charts


Miscellaneous
1.critical to quality-attribute most important to customer
2.defect-failing to deliver what customer wants
3.variation-what customer sees and feels
4.Process capability-what our process can deliver
5. stable operations-ensuring consistent,predictable processes to improve the
variation
6.design of six sigma- designing to met customer needs and process capability