Six Sigma Interview Preparation Guide

The measure of variation in a process which is statistical in nature is known as Sigma. The Six Sigma process is derived if the quality is 3.4 Defect per Million Opportunities (DPMO). Six Sigma is a problem solving methodology. This methodology is applicable to a process for eliminating the root cause of defects and the costs that are associated with the same.

It is a methodology and set of tools for the measurement of process quality. It demonstrates that the business process is well controlled. Six Sigma level can be achieved when the accuracy of your process gets only 3.4 defects per million opportunities.

Here’s the list of acceptable number of defects per million to correspond to each Sigma level:

Sigma level Defects per million opportunities
1 690,000
2 308,537
3 66,807
4 6,210
5 233
6 3.4

The following are the kids of variations used in SIX Sigma:

Mean: The variations are measured and compared using the averaging techniques of mathematics. The measures are taken for a specific application and the mean is calculated

Median: The variations are measured and compared using the mid point in a given range of data. It is measured by finding the highest and lowest value then dividing it by two. The lowest value is added to the same

Range: The values of a specific data range. It is the difference between highest and lowest values in a specific data range.

Mode: Mode is the most occurred values in a given data range.

Six Sigma aims to deliver quality products to the customers. It also intends to reduce output variation by predicting process results. Processes here would be measure, analyze, improve and control, Variation here means how much has the output deviated from the actual. Six sigma means as the process deviation increases the sigma number is decreased. Having the sigma number as 6 would mean that there will be no items that don’t meet with the specifications.

Reduction variations is the strategy of Six Sigma approach. Standard deviation which is a square root of variance is the measure of variations. The approach is to reduce the sigma value and the better process experience.
However , there are two other types of variations, namely, Operator origin variations ...measured as Reproducibility and Guage variations ...repeatability is another element of Guage variations coming from operator origin.Measurement system analysis deals withis types of variations.
There is another aspect of looking at the multiple sample variations by way of ANOVA

Six Sigma implementation team has five key players:

Executive leaders
Champions
Master black belt
Black belts
Green belts

Executive leaders: The decision of to six sigma is taken by the main team – Executive Leaders. They promote the six sigma throughout the enterprise and ensure the commitment of the enterprise in six sigma. The executive leaders are mainly CEO, or some of the board of directors. The six sigma initiative is funded by Executive leaders. The executive leaders should be confident and determine that six sigma will improve organization process and it is succeeded.

Champions: Champions are normally the senior manager of the enterprise. He promotes six sigma mainly among the users of the business. He acts as a coach, mentor, selects projects, decides the objectives, allocates the resources and removes hurdles from black belt players. The champions fight for removing black belt hurdles.

Master Black-Belt: This role highly demands the technical capability in six sigma. All organizations are not started with six sigma and will not have the same. Normally outsiders are recruited for it. The key role of Master Black-belt is train, mentor and guide. He supports the executive leaders in candidate’s selection; teach the fundamentals and train resources and right project for resources.

Black-Belt: Black-belt always leads a selected project team for show casing six sigma. Their responsibilities include finding out the variations and looking after minimizing the variations. Black belt normally selects the projects, train resources, and they are the real implementers of the project. They are the core resources to six sigma as the actual implementation of six sigma is done by black belt, in the enterprise.

Green Belt: The green belt resources supports black belt in the functionality areas. They are part time resources who work mainly on projects for six sigma implementation. The six sigma methodologies for solving problems are applied by green belt and help for defining the basic six sigma implementation of the enterprise. The too support black belt in implementing six sigma in the enterprise.

Attaining Six Sigma is a team effort. An organization who wants to attain Six Sigma needs a lot of restructuring and change in attitude. It includes building up the following roles to take up the required responsibilities:

1. Executive Leadership-Includes CEO and other top management team members. They set up the vision of Six Sigma and empower their team mates with the freedom and resources required for the improvements in the process.
2. Champions- Responsible for the implementation of the process in an integrated manner through out the organization. They come from Top management.
3. Master Black Belts-Act as in-house expert coach for the organization. They assist Champions and train Black Belts and Green Belts.
4. Black Belts-Apply Six Sigma methodology to specific projects. Their focus is on execution of activities for Six Sigma.
5. Green Belts-These are like the soldiers on the war front who actually implement the planned action.

In order to express the amount of business functionality of an information system, a function point is used as a unit of measurement.

There is International Function Point Users Group in US based organization of users of the software metric Function Point Analysis

Every function point is a unit of measure used by IFPUG functional size measurement method.

The IFPUG FSM is one of the currently recognized standards of ISO for functionally sizing software.

The DMAIC project methodology has five phases:

Define the problem, the voice of the customer, and the project goals, specifically.
Measure key aspects of the current process and collect relevant data.
Analyze the data to investigate and verify cause-and-effect relationships. Determine what the relationships are, and attempt to ensure that all factors have been considered. Seek out root cause of the defect under investigation.
Improve or optimize the current process based upon data analysis using techniques such as design of experiments, poka yoke or mistake proofing, and standard work to create a new, future state process. Set up pilot runs to establish process capability.
Control the future state process to ensure that any deviations from target are corrected before they result in defects. Implement control systems such as statistical process control, production boards, visual workplaces, and continuously monitor the process.