Establish Process Capability

By Dave Litten
About Establish Process Capability

Establish Process Capability

Define Measure Analyse Improve Control

define measure analyse improve control

Process Capability is the ability of the process to deliver as per the customer requirement.

There are various process capability indices, but in Lean Six Sigma projects, sigma capability is the most often-used measure as it gives an accurate report on the current process performance.

The outcome of a Process Capability study can be used to validate the process objectives and anticipated benefits in the charter. If needed, the Lean Six Sigma project charter can be revisited.

On completion of the above deliverable, and a formal Measure Phase gate review, the team is ready to move into Analyze phase.

The Analyze Phase of a Lean Six Sigma Project

Analyze Phase of Lean Six Sigma Project is the third phase. Following are the deliverable of this phase that Six Sigma Green Belt should deliver with her team:

  • Statistically validate root causes
  • Perform Value Stream Mapping & Process Value Analysis
  • Control & Impact Matrix

Statistically Validate Root Causes

The data that has been collected in the Measure Phase is used to draw statistical associations between CTQ measures and causes. The causes that are statistically significant are the root causes.

There are a variety of statistical tools to establish this association. Depending on the type of data – continuous or discrete – tools are selected. Such tests are generally called as Hypothesis tests. 2-t Test, Z-test, t-test, ANOVA, Chi-Square Test, Correlation, Regression, etc., are few common hypothesis tests.

Perform Value Stream Mapping & Process Value Analysis

Value Stream Mapping (VSM) is a popular tool used in Lean methodology; as an alternate approach to statistically identifying Root Causes, or in conjunction with it is the application of Value Stream Mapping and Process Value Analysis.

It is used to identify the 7 types of Wastes (Muda – in Japanese) in a process. VSM is a holistic method to visually document the way in which value is getting built in a process.

The 7 types of process wastes are generally referred to as Non-Value-Added tasks in conventional Six Sigma.

The procedure of associating every task in a process as either Value Adding (VA), Non-Value Adding (NVA), or Value-Enabling (VE) is called as Process Value Analysis.

These methods are very useful in projects where extensive data collection is not possible, or in projects with Turn-Around Time or Delay reduction.

Control-Impact Matrix

The final deliverable of the Analyze phase is to summarize all the findings from Statistical validation or Process Value Analysis (& VSM) in a 2×2 matrix called a Control-Impact Matrix.

It is important to ensure that the project doesn’t end up as an academic exercise or research study. Hence, the Lean Six Sigma team needs to identify root causes which have high impact, and well within the control of the team. This is done through a team discussion with the involvement of the project sponsor.

Once the root causes have been identified, & a formal Analyze Tollgate review is completed; the Lean Six Sigma Project is ready to move to the Improve Phase.

Pen