Q 302. Process Door and Data Door are two methods used for identification of critical causes in Analyze phase. What is the difference between the two? Also highlight the tools that are used in each of the two methods.

 

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In Analyze phase of DMAIC, Xs’ (or causes) are identified basis different methodology of which Brainstorming is widely used.

Post identification of X’s prioritization of X’s are done, where impact of X’s are studied over Y (effect). Prioritization could be performed by 2 ways “Data door or Process Door”

 

Data door- For all the X’s where data is quantitative in nature (which can be measured). Data door method is taken. Commonly used tool for Data door approach are:

Graphical Analysis: Trend Chart, Run Chats, Control Chats, Histogram etc

Hypothesis Testing: Annova, Regression, Multiple Regression, Chi Sq etc

For eg: if Low Accuracy is the Y for the project then potential Xs’ qualified for data door could be: “Accuracy score between employees, Volume arriving pattern vs Accuracy, Transactions type with respect to accuracy”

 

Process door- At time there are X’s for which data is more of qualitative in nature (knowledge based upon Process experience) Process Door method is adopted.

Commonly used tools are “Process Maps, Fish bone Diagram, RCA etc”

For eg: if Low Accuracy is the Y for the project then potential Xs’ qualified for Process door could be: “Learning Curve of Employee, Work Environment impact on Accuracy etc”

In order to answer the question 'Why is the problem occurring?", below steps are done in Analyze phase

 

1. List all potential causes

2. Analyze potential causes

3. Identify critical causes

 

 

There are 2 approaches that can be deployed for analyzing potential causes. I have summarized both in the table below

 

 

P.S. the usage of tools is not exclusive i.e. tools can be used either for process or data door depending on the situation. The table only highlights the preferred or the most commonly used tools.

 

 

Benchmark Six Sigma Expert View by Venugopal R

One of the main intent for executing a project using the six sigma methodology is to guide a team through a disciplined approach to solve a problem in a highly objective manner. Various terminologies have been coined to reinforce the disciplined approach. “Process Door” and “Data Door” are terms used to broadly classify the approach to be used during the Analyze phase. Ironically, though one of the approaches is termed as “Data Door”, it does not mean that the “Process Door” will not use Data!

 

Effectiveness and Efficiency

First, let us understand that the objective for any Six Sigma Project may be broadly classified as “Effectiveness improvement” or “Efficiency Improvement”.

 

'Effectiveness' refers to how effectively we deliver a product or service to a customer, internal or external. Improvements in Product Quality, Enhancing performance of a product, Improving Process capability, Reducing variation, Improving Market share etc. are examples of Effectiveness improvement.

 

'Efficiency' refers to providing an higher effective output with lower inputs. Lean Projects in general are ‘efficiency improvement’ projects. Improving Cycle Times, Reducing wastes, Resource Optimization are examples of 'Efficiency Improvement'.

 

Process door and Data door

Once we define a project, go through the ‘Measure’ phase and reach the ‘Analyze’ phase, the choice of ‘Process Door’ or ‘Data Door’ has to be made. In general, ‘Effectiveness improvement’ projects take the ‘Data Door’, whereas ‘Efficiency Improvement’ projects take the ‘Process Door’.

 

Data door

For ‘Effectiveness improvement’ projects we will usually have a target, standard or specification, which has to be complied or attained. By the Data Door approach, 'the current situation analysis' will give us the gap which has to be studied using tools such as Pareto analysis, Control charts, Histograms, Scatter Plots, Design and Process FMEAs etc.

 

Statistical tools such as Confidence intervals, Hypothesis testing, Normality, Correlation & regression etc. are also applicable as required.

 

Process door

For ‘Efficiency improvement’ projects, the approach normally starts with a process map and identification of valued adding and non-value adding (NVA) process steps.  There are detailed definitions for NVAs. A quick definition for NVA would be – those process steps for which: customer is not willing to pay for, or does not result in any physical transformation, or happens to be a re-work.

 

Some of the tools used in Process door are Process mapping, Effort vs Elapsed time, Seven+ wastes, VSM, Process FMEA etc. While using these tools, it is possible that some of the earlier mentioned statistical tools in Data door such as Pareto, Hypotheses may also be used as necessary.

 

Practical application on projects

For many projects, it may not be right to strictly stick to a set of tools under one of these ‘doors’.  

 

For instance, while working on a project that is trying to improve the number of exterior damages on a consumer durable product, the analysis might throw up ‘Number of instances of product handling’ as a possible cause. Then, it might lead to the process door, and process study has to be done to identify the number of ‘handling steps’ that could be avoided. This is one of the '7+ wastes'; hence, apart from the main objective, the project would also give some efficiency related benefits.

 

Similarly, a project that begins as an efficiency improvement project, let’s say the TAT improvement for a loan processing begins with a 'Process door' – upon analysis, we might discover that 'reworking errors' as one of the possible causes. This will lead us to the ‘Data door’ to drill down on the details of the errors made, their causes and remedies.

 

Sum up

Once a project is defined, the team is expected to have a clear idea about the problem statement and the objective, based on which they will be led to the approach and tools as applicable to the situation. The concept of Process Door and Data Door is intended to provide an over all guidance to get them on the appropriate direction. The team will open the appropriate ‘doors’ and apply the tools while they traverse the course taken by the project.

The Process Door and Data Door

In DMAIC process, analysis phase is very important phase to analysis the data and there are many tools & techniques which are used for analysing data however some challenges to use right tool & techniques in right situation.

Process door and data door are useful to divide the analysis phase into two section which is useful to get the actual analysis.

Process Door

Process door apply to a section of tools & technique that help to understand and get a clue from process directly. below tools generally use in process door

1.     Process mapping technique

2.     Seven wastes

3.     Measles charts

4.     Root cause analysis tool (brainstorming, Fishbone diagram ,5 whys)

5.     FMEA

Data Door

Data door apply to a section of tools & technique that help to understand process from the data itself and below tools generally use in Data door

1.     Graphical Analysis tool (Histograms, run chart, Box chart, Scatter Plots, Dot plots)

2.     Statistical Analysis tool (Confidence interval, hypothesis testing, corelation & recreation, Normality testing)

All the published answers are correct and are winners for this question.

 

Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.