Category Archives: Six Sigma Tools

The cause and effect diagram is used to identify and discover all the potential or real causes (or inputs) that will lead to or result in a single effect (or output). The arrangement of the causes is done according to their level of importance or detail which results in a depiction of relationships and hierarchy of events.

It helps in finding the root causes, identifying  the problematic areas and comparing the relative importance of different causes. It is also used to the organization diagramming, parts hierarchies, project planning, tree diagrams, and the 5 Why’s.

The C&E diagram is also famous as the fishbone diagram because it resembles the skeleton of a fish, with the main causes categories drawn as “bones” attached to the spine of the fish.

Chi-square test

A chi-square test (also chi-squared or ?2  test) is any statistical hypothesis test  used to compare observed data with data we would expect to obtain according to a specific hypothesis and in which the sampling distribution of the test statistic is a chi-square distribution when the null hypothesis is true.

Chi-square test  practices null hypothesis, which states that there is no significant difference between the expected and observed result in an event.

Some examples of chi-squared tests are Pearson’s chi-square test, Yates’ chi-square test, Mantel-Haenszel chi-square test, Linear-by-linear association chi-square test, The portmanteau test in time-series analysis, testing for the presence of autocorrelation.

Control Charts

The control chart, also known as the Shewhart chart or process-behaviour chart, is a tool used in statistical process control for determining  whether a business process is in a state of statistical control or not. It is also known as a special-cause variation.

All points will be plotted within the control limits in case the process is in control,. Any observations outside the limits suggests  the introduction of a source of variation which is new and unanticipated.

As increased variation means increased quality costs, a control chart revealing  the presence of a special-cause calls for immediate investigation. Thus the control limits are a crucial decision aids. The control limits suggests about process behaviour .

Cause & Effects Diagram PPT

Six Sigma Tools

Six sigma tools are the Quality Management techniques, approaches and methodologies used in Six Sigma for the process improvement in an organization. Appropriate implementation of these tools brings about amazing results.

In the beginning of a new process, the effective application of these tools and techniques ensures successful implementation of Six Sigma Quality initiatives.

Six Sigma uses  a great number of established quality management tools and methods which are applied not only in Six Sigma projects but also outside applications as well.

Affinity Diagram

The objective for the development of affinity diagram was discovering meaningful groups of ideas within a raw list. It emphasize on allowing the groupings emerge naturally by using the right side of the brain. Basically it is used to refine a brainstorm into something which can be dealt more easily and that makes sense.

Ishikawa recommends using the affinity diagram in variety of situations like when facts or thoughts are unorganized and not certain, to overcome preexisting ideas or paradigms, to clarify the ideas  and when unity within a team is required.

Analysis of Variance

Analysis of variance (ANOVA) is a statistical term which defines the collection of statistical models with their  associated procedures. Here the observed variance is partitioned into components because of different explanatory variables. Simply, ANOVA produces a statistical test of whether the means of several groups are all equal

Basically, there are three conceptual classes of statistical models:

Fixed-effects models (Model 1): It  is based on the assumption that  the data coming from normal populations which are differing  only in their means.

Random effects models (Model 2) : It is based on the assumption that the description of data reveals a hierarchy of different populations whose differences are constrained by the hierarchy.

Mixed-effect models(Model 3): It explains the scenarios where there is presence of  both fixed and random effects.

Usually  there are several types of ANOVA depending on the number of treatments and the way they are applied like one way Anova,  Factorial Anova, mixed design Anova.

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Six Sigma and Innovation

Every organization needs to innovate itself times and again to survive and consistently perform in the competitive environment.  Innovation is something new and contrary to established manners or practices.  A new idea has to overcome a lot of resistance to become a reality.

Six Sigma focuses on the customer satisfaction that leads to profitability and thus aims at reducing variation. This goes against the principles of innovation. Therefore the relationship between Six Sigma and Innovation is both complementary and opposite to each other.

Comparison between Six Sigma and Innovation is as follows:

(1)    Six Sigma drives out the variation from the system, while innovation encourages the diverse thinking.

(2)    Six Sigma optimizes the processes and product tradeoffs however innovation relies on breaking the mold so that the tradeoffs are not necessary.

(3)    Six Sigma focuses on precision and is basically data driven while innovation leads to the creation of emotional experiences.

(4)    The basic aim of the Six Sigma lies in making the organization profitable by increasing the cash flow however the innovation stresses on taking the calculated risks.

Various levels of innovation are as follows:

(1)   Customer Interface: Innovation is about generating novel ideas and ways that lead to creation of commercial value.  This level exploits the market opportunities through better ways to connect existing capabilities with the existing needs.

(2)   Core Strategy:  It assist in expanding the market opportunities by connecting the existing capabilities to new needs.  It focuses on mission differentiation criteria against competitors.

(3)   Strategic Resources:  This level expands market opportunities by connecting the new capabilities to existing needs.  It includes the core competence, key strategic assets and processes.

(4)   Value Network: This level creates new markets by developing new capabilities to meet new needs and it includes the suppliers, partners and coalitions.

Six Sigma Calculation And Calculators

Six Sigma Calculator:

Six sigma metrics comprises of the different types of measurements that are applied in six sigma methodology. Getting the right measurement through the use of Six Sigma Metrics requires the application of these metrics in the right context. Innovative ways are needed to resolve the customer’s issues and improve the quality of the products.

Certain steps are necessary to be followed in correct sequence so that Six Sigma measures are calculated without any defects. Six Sigma calculator is the tool that is applied for the measurement of the quality in Six Sigma Metrics.

Six Sigma Metrics used for the calculation of Sigma Level are as follows:

Defects Per Million Opportunity (DPMO):  The calculation of the Sigma level is done on the basis of number of defects per million opportunities(DPMO). For the calculation of DPMO, three distinct pieces of information is needed

(1)   The No of Units produced

(2)   The No of defect opportunities per unit

(3)   The number of defects

Actual formula applied is as follows:

DPMO = (Number of defects * 1,000,000)/ (No of defect opportunities per unit)*(no of units)

Critical To Quality (CTQ):   Applying the CTQ is the key for measuring any product or process, whose performance standards must be met consistently for satisfying and exceeding the customer needs. CTQ should be actionable, and imply quantitative business specification.

Sample Size Calculator:

It is an excel spreadsheet that is applied as a tool for the Sigma Level Calculation. It is used for the determination of the number of data points or sample size. It is for the elimination of the properties of population

Three types of six sigma level calculator are as  follows:

Sigma level form DPMO

Sigma level from Quality Yield

Sigma level for DPM for Non Centered Process

Process Sigma Calculator:  This is used for defining the unit, opportunity, defect, DPU, DPMO, defects(%), and yield (%) in a Six Sigma Project.

Six Sigma Metrics

A Six Sigma metric is a standard measure for assessing the project performance in a particular area. Metrics are applied rigorously in any customer-focused process management system and any program targeted at continuous improvement.

In a Six Sigma project. the focus on customers and its performance standards shows up in the form of metrics  that assess project’s ability to meet their  customers’ demands  and business objectives.

Six Sigma Metrics can be categorized as Classical Metrics and Typical Metrics.

Classical Metrics It contains measures of quality involving timeliness, accuracy, ease of doing business and cost. They are important and emphasis is given on them as vital aspects of most companies’ Six Sigma measurement framework.

Typical Metrics It contains various specialized measures like DPMO, DPU, FPY, RTY and Sigma Level. A Sigma Metric offers an effective alternative to traditional process capability and performance measures as used in Statistical Process Control.

DPMO is a Six Sigma Metric which stands for ‘Defects Per Million Opportunities’ .  Six Sigma process improvement projects targets  to achieve 3.4 or fewer Defects Per Million Opportunities.  DPMO is usd to compare the defect rates of simple and complex items and provides a common standard.

DPU is a Six Sigma Metric which stands for ‘Defects Per Unit’.  It refers to the average number of defects per unit based on the processing of a number of units. For example if 100 units are made and five fail, four reworked, and one scrapped then DPU is 0.05.

The First Pass Yield is the proportion of units that, on average, go through a process first time without defects in a Six Sigma project

Rolled Throughput Yield (RTY) is a  probability that a unit can pass through a process without defects ina Six Sigma project.  It is result of the product of the first pass yields at every step:

RTY = y1 x y2 x y3 x ………..yn

where the yi values are the yields at each step before rework

Implementation of Six Sigma Metrices

The implementation of Six Sigma Metrics requires a systematic approach so that effective utilization of metrics in assessing the performance standards is done.

The first step is about measuring the right things which not only includes the financial performance but also other aspects of the business like customers,  performance of internal work process,  suppliers, financial and employee satisfaction as well.

Second step is to create the metrics which are SMART an acronym for Specific, Measurable, Actionable, Relevant, and Timely.

Specific means Metrics are specific and directed at a particular area you are measuring.

Measurable means to collect accurate and complete data.

Actionable means that clarity over which direction to take and easy to understand and to take action.

Relevant means measuring only meaningful things, determine effective measures, including both performance and diagnostic metrics.

Timely means  getting the data whenever required.

Metrics should be simple and can be categorized into performance Metrics and diagnostic Metrics.

Performance Metrics means high level measures which are external in nature and are related to the customer requirements, business needs and outputs.

Diagnostic Metrics means measures which are internally focused and related to inputs and internal process steps.

Third Step is following a well proven method for developing metrics. It involves the identification of the customers and outputs of the process, determination of customer’s requirements, ensuring the key goals of the business and aligning the metric for the process with those of high level processes.

After the metrics are determined as what needs to be measured, a check needs to be done to ensure if the metrics are making any sense, how they can be compared with the existing metrics, do they form a complete set  covering the areas like time, quality, cost, and customer satisfaction and whether they display the desired behavior.

Six Sigma Process Maps and Flowcharts

Process mapping is a renowned  technique for the creation of  a common vision and shared language which leads to the improvements in business results.  It is usually the first step in the implementation of Six Sigma project.  Process Maps and Flow Charts displays the activities in a process in a sequential manner.

Process Maps are more detailed than flowcharts and includes a timeline.  Process Map is basically a  graphical representation of a procedure that  displays  a flow of a process and is  used for detection of shortcomings in a process.  Process Map includes the usage of  Flowcharts and Block Diagrams.

The graph in a Process Map  includes the  starting points and ending points of various processes and sub processes, inputs,  outputs  and potential direction.  Mapping of an entire process in detail needs  several sub-process maps in addition to overview process map or a Complex Block Diagram.

Flowcharts

A flowchart is a representation of a process graphically where it displays the entire process from beginning to finish, showing various inputs, pathways with directions, action or decision points and completion of the process. It basically serve as an instruction manual for facilitating detailed analysis and optimizing the workflow and service delivery.

Block Diagram- flowchart

Block Diagram is basically a graphical tool which make use of the picture of any given process. It depicts the design of the networking of its various components as well as the logical flow of the process or the procedure. Each item is represented by a different shape.

Process is indicated by the “rectangle shape.

Connector is indiacted by “circle shape.

Extract is indicated by  “triangle shape.

Decision is indicated by diamond shape.

Using flowcharts assist in successful implementing of  Six Sigma project.

Complex Block Diagram

It includes the assorted block diagrams which are tied at various points in order to follow the complete procedure. It contains  an analogy process and various sequenced processes.

Six Sigma Statistics

Six Sigma apples a wide variety of statistics for the determination of  best practices for deployment of Six Sigma projects.  Statisticians and Six Sigma consultants devise new methods which are based on the studies and experimentations of existed processes.

Statistically, Six Sigma ensures that about 99.9997% of all products produced are of acceptable quality. Some of the popularized statistical tools are as follows.

Control Charts / SPC

Minitab’s suite of control charts and powerful SPC capabilities helps in controlling the processes effectively. It offers tools for identifying the problems in the processes.  Process statistics can be tracked over time with the help of the SPC tools like control charts and the special causes can be identified which may pose threat to the  procedure.

Data / Sampling / Descriptive Statistics and Hypothesis Testing

Minitab 15 includes various  tools and guidance for satisfying the quality improvement projects. Minitab offers the complete range of basic statistical procedures which can be applied for simple estimation and hypothesis testing. It contains descriptive statistics and graphics, hypothesis tests and confidence intervals, variance, and association.

Measurement System Analysis (MSA) and Gage R&R

Minitab 15 includes the gage analyses and related tools to maintain higher standards of quality of  the process data. Minitab contains  a full suite of Measurement Systems Analysis commands to check the measurement system.

Online Statistics Textbooks

Online books contain Computer-Assisted Statistics Teaching and a highly interactive online textbook that includes dynamic displays like animations and simulations. It presents computer-based training based on data centered approach.

Process Capability / Capability Indices

The capability index is useful for measuring the continual improvement using trends over time, for  prioritizing the order leading to process improvement and for determining process capability in meeting customer requirements.

Others Statistical tools includes  Rational Subgroups and Subgrouping, regression analysis, SigmaXL, Variation.

Six Sigma Softwares

Basically there are three classes of software used for the implementation of Six Sigma methodology.

(1)    Analysis tools: They are used to perform statistical or process analysis.  Six Sigma methodology applies the advanced statistical solutions to the complex problems for process improvement and these tools make life easier for the professionals.

Some of the widely used tools are as follows

(a)   Microsoft Visio: It is a Microsoft Windows program that is diagramming in nature and uses vector graphics for the creation of diagrams. It comes in two editions: Standard and Professional.  They have templates for advanced diagrams and layouts and possess unique functionality which helps users to connect their diagrams to a number of data sources in addition to displaying the information graphically.

(b)   Minitab is basically a statistics package used as an analysis tool distributed by Minitab Inc. It is often used in along with Six Sigma implementation, CMMI and other statistics-based process improvement methods.  Minitab 15 is the latest version which is available in 6 different languages (English, French, German, Korean, Simplified Chinese, & Spanish).

(c)     STATISTICA : It is is a statistics and analytics software package which provides a selection of data analysis, data visualization, data management, and data mining procedures. It is developed by StatSoft.

Other famous analysis tools which are commonly used are iGrafx process, IBM websphere Buiness Modeler, JMP, SigmaXL,  Statgraphics,Telelogic System Architect, etc.

(2)    Program management tools : They are the set of tool which are used to manage and track a the entire Six Sigma program of a corporation.

(3)   DMAIC and Lean online project collaboration tools: These are the softwares which assist in implementation of Six Sigma across  local and global teams. They help in effective management of the projects.  One very famous Example is Grouputer Sigmasense.

Six Sigma as a path breaking  methodology for the business improvement has its own advantages and disadvantages.

(1)   Six Sigma is driven by the customer and thus aims to achieve maximum customer satisfaction and minimizing the defects. It targets the customer delight and new innovative ways to exceed the customer expectations.

(2)   Implementation of Six Sigma methodology leads to rise of profitability and reduction in costs. Thus improvements achieved are directly related to financial results.

(3)   Six Sigma is successfully implemented in virtually every business category including return on sales, return on investment, employment growth and stock value growth.

(4)   Six Sigma targets Variation in the processes and focuses on the process improvement rather than final outcome.

(5)   Six Sigma is prospective methodology as compared to other quality programs as it focuses on prevention on defects rather than fixing it.

(6)   It is attentive to the entire business processes and training is integral to the management system where the top down approach ensures that every good thing is capitalized and every bad thing is quickly removed.

(1)   Applicability of Six Sigma is being argued among the Six Sigma critics. They opined that the quality standards should be according to specific task and measuring 3.4 defects per million as standard leads to more time spent in areas which are less profitable.

(2)   Six Sigma gives emphasis on the rigidity of the process which basically contradicts the innovation and kills the creativity. The innovative approach implies deviations in production, the redundancy, the unusual solutions, insufficient study which are opposite to Six Sigma principles.

(3)   People argue that Six Sigma is a bit gimmicky and simply a rebranding of the continues improvement techniques and tools as practiced by Toyota. It thus promotes outsourcing of improvement projects with lack of accountability.

(4)   Six Sigma implementation constantly require skilled man force. Thus control and employee dedication are hard to accomplish if its not implemented regularly.

(5)    While converting the theoretical concepts into practical applications there are lot to real time barriers which needs to be resolved.

Six Sigma Case Studies

Case Study is defined as research strategy, which investigates the phenomenon with in  real life scenario. It may include single and multiple case studies. It involves quantitative and qualitative evidence relying on multiple sources and benefits from prior developments.

Six Sigma case study talks about building up of the framework, related to the implementation of Six Sigma methodology in the minds of the organizations. Case studies are developed basically on the benefits of Six Sigma methodology leading to growth and improvement of organization and a project.

Case studies are made on wide range of fields across the business and industrial sector like IT, call centers, large companies based in the US and India etc. This case study provides useful insight into the areas where Six Sigma is being applied and what aspects of Six Sigma is more effective and adopted by the organizations for their success in terms of quality, performance and cost reduction.

Case studies reveal that DMAIC is more frequently used Six Sigma methodology.  Some of the key aspects in which the help of Six Sigma is used for developing the case studies made are as follows:

(1)    Identifying the problems and their root cause

(2)    Identifying  the defects of the products

(3)    Formulation of ideas to avoid the defects

(4)    Idea testing and modifications

(5)    Implementing  the modified products

(6)    Confirming and monitoring  the product results

(7)    Tracking the improvement and the customer satisfaction

(8)    Focusing on Long term quality improvement

(9)    Inculcating the six sigma techniques and mind-set

Adopting a Business Process Approach to Management requires various critical steps by the organizations.  Case study reveals that critical steps required for the successful implementation of DMAIC are determining the Customers and Stakeholders and benefits organization is providing them, determining the value chain that deliver benefits, identifying process boundaries, selecting the process owner for each process, beginning of never ending cycle Business Process Improvement, etc.

Examples of Six Sigma Case Studies

Application of Six Sigma DMAIC methodology has resulted in vast improvement in the performance of organization as evident by the numerous success stories across the globe. Some examples of the case studies are as follows.

(1)   Oil exploration and drilling company.  Project was to Improve automatic well test process.  Results : Increase in test accuracy by 25% and Improvement in  % of successful “workovers”.

(2)    Vehicle maintenance support unit . Project was reduction of the high cost of vehicle maintenance. Results : Moving  technical experts to the field and Improved data collection techniques

(3)   Large Electronics Company. Project was to Deflect  yoke for TV.  Results : Upgradation of the design using DFSS tools and improvement in overall production process

(4)   Automotive Project was failures of Crankshaft production  Results : Application of Six Sigma tools to stratify the errors which were due to grinding failures.

(5)   Pharmaceutical Company. Project was Packaging- downtime of machines on the packing line was excessive leading to lower than expected productivity Results :   SOPs were developed,   improvement in Training and Variation in the adjustments and reduction of adjustment frequencies.

(6)   Chemical Production Project was to  improve production capacity and reduce variability of Methyl Ethyl Ketone (MEK) and Ethanol Separation Unit.  Results : improvement of Normal production rates for MEK and Ethanol by more than 4% above previous maximum rate and decrease in Ethanol losses.

(7)    Transactional Project was  reduction in Employee productivity when employees transfer to different jobs within the company.  Results : Lost productivity resulted because of failure of direct deposits, interrupted health care, increase in out-of-pocket expenses, etc. DMAIC process leading to improved process flows.

(8)    Medical Device Company Project  was Combining the  two existing rejection systems used for tracking defective materials. Results :  The two systems were combined, streamlined, and placed on the web and creation of Process flow for new process