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.