Six Sigma Bar Diagram

LEAN SIX SIGMA PART…. 18 MARATHON STUDY

‘’In my last article, we learned Six Sigma DMAIC Process - Measure Phase - Process Capability

Please read along as we attain another height in PART..18..

We progress by understanding Six Sigma Bar Diagram

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Six Sigma Bar Diagram

?Pie Chart:

A pie chart is a graphical representation of attribute data. The “pieces” represent proportions of count categories in the overall situation. Pie charts show the relationship among quantities by dividing the whole pie (100%) into wedges or smaller percentages.

Six Sigma Pie Chart

Cause and Effect Diagram / Fish Bone Diagram / Ishikawa Diagram:

This is a visual tool used to brainstorm the probable causes for a particular effect to occur. Effect or the problem is analogously captured as the head of the fish and thus the name. The causes for this effect or problem is generated through team brainstorming and are captured along the bones of the fish. The causes generated in the brainstorming exercises by the team will depend on how closely the team is related to the problem. Typically the causes are captured under predetermined categories such as 6M’s or 5M’s and a P as given below:

???????? Machine: This category groups root causes related to tools used to execute the process.

???????? Material: This category groups root causes related to information and forms needed to execute the process.

???????? Nature: This category groups root causes related to our work environment, market conditions, and regulatory issues.

???????? Measure: This category groups root causes related to the process measurement.

???????? Method: This category groups root causes related to procedures, hand-offs, input-output issues.

???????? People: This category groups root causes related people and organizations.

Below is an example of a fishbone diagram created for capturing the root causes of High Turn Around Time (TAT).

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Six Sigma Cause and Effect Diagram / Fish Bone Diagram / Ishikawa Diagram

Pareto Chart:

A data display tool for numerical data that breaks down discrete observations into separate categories for the purpose of identifying the "vital few”

Six Sigma Pareto Chart

Histogram:

A histogram is a graphical representation of numerical data. It is constructed by placing the class intervals on the horizontal axis of a graph and the frequencies on the vertical axis.

Six Sigma Histogram

Box Plot:

A box plot summarizes information about the shape, dispersion, center of process data and also helps spot outliers in the data.

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Six Sigma Box Plot

The box plot can be interpreted as follows:

???????? Box – represents the middle 50% values of the process data.

???????? Median – represents the point for which 50% of the data points are above and 50% are below the line.

???????? Q1, Q3 – Q1 represents the point for which 25% of the data points are above and 75% are below the line; While, Q3 represents the point for which 75% of the data are above and 25% are below in the line.

???????? Aestrix – represents an outlier and is a point which is more than 1.5 times the inter-quartile range (Q3-Q1) in the data.

???????? Lines – These vertical lines represent a whisker which joins Q1 or Q3 with the farthest data-point but other than an outlier.

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Example: Below is an example of a call center process where Average Handle Time (AHT) of the calls is compared between Team Leads of the process.

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You will observe that the variation is highest for TL1 and for the rest it is much smaller. This indicates that the associates working under TL1 need training or some other help which will reduce the variation and bring the overall AHT under control.

Scatter Plot:

A scatter plot is often employed to identify potential associations between two variables, where one may be considered to be an explanatory variable (such as years of education) and another may be considered a response variable (such as annual income).

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Six Sigma Box Plot Example

Scatter plots are similar to line graphs in that they use horizontal and vertical axes to plot, large body of, data

points. And, they have a very specific purpose too:

???????? They show how much one variable is affected by another variable and this relationship is called as their correlation.

???????? The closer the data points come when plotted to making a straight line, higher is the correlation between variables.

???????? If the data points make a straight line going from the origin out to high x- and y-values, then the variables are said to have a +ve correlation.

???????? If the line goes from a high-value on y-axis down to a high-value on x-axis, the variables have –ve correlation.

Once after identifying the factors we need to

???????? What is the extent of impact of the factors?

???????? Which one do you control?

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Six Sigma Scatter Plo?

Scatter plots are similar to line graphs in that they use horizontal and vertical axes to plot, large body of, data points. And, they have a very specific purpose too:

???????? They show how much one variable is affected by another variable and this relationship is called as their correlation.

???????? The closer the data points come when plotted to making a straight line, higher is the correlation between variables.

???????? If the data points make a straight line going from the origin out to high x- and y-values, then the variables are said to have a +ve correlation.

???????? If the line goes from a high-value on y-axis down to a high-value on x-axis, the variables have –ve correlation.

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Once after identifying the factors we need to

???????? What is the extent of impact of the factors?

???????? Which one do you control?

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Six Sigma DMAIC Process - Analyze Phase - Control Impact Matrix

This is a prioritization tool that is used in conjunction with the C&E tool typically after the causes have been captured using C&E. Prioritization is done based on factors (causes) that are in your control and the impact (extent) of the factor on the problem or the effect

Six Sigma Control Impact Matrix

We generate the factors/causes using the C&E (Cause and Effect) matrix. Followed by verification of this qualitative assessment of the factors/causes by seeking data, which can then be prioritized using the control impact matrix or Pareto analysis. But are these the root causes? Or do we need to drill down further?

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How do we do it?

Ask Why five times OR Ask why till a time when you do not have an answer to the Why OR The final answer that you may get could be a root cause.

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Six Sigma DMAIC Process - Analyze Phase - Why Analysis

Why Analysis is explained through the below example:

???????? Why does the Home finance loan application process take more than 10 working days to arrive at the decision of “Credit Worthy”? Because many application received especially by Post have fields that are either not clear or left blank.

???????? Why do we have applications that have blank fields? Because the customer did not fill out the details.

???????? Why did the customer not fill the details? Because they were not clear.

???????? Why were they not clear? Because the direction was not clear.

???????? Why were the direction not clear? Because many of the customers never read them.

???????? Why did they not read them? Because the print was too small.

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Thanks For Learning With Maxwell Stay close for part ,,,,18,,,,,

Next we shall study Six Sigma DMAIC Process