Capability is the most important measure to define whether candidate NUD Xs and Ys are truly critical. Capability indices are the ultimate expression of how well a NUD function or characteristic is meeting customer-based requirements. They are the confluence of expected performance in ratio with actual, measured performance (mean and standard deviation). They form the basis for the summary metric called the Capability Growth Index which is equally, if not more, important than growth metrics for product reliability.

Required vs. Measured: Capability

Required CPM Data for any form of Capability Assessment

1. All functional responses (Y) or design characteristics (X) that support a functional response (Y) must have a capable measurement process documented and in use (Gage R&R Study).
2. Each functional response (Y) or design characteristic (X) that supports a functional response (Y) must be placed under stable SPC so the Cp and Cpk can be routinely quantified for phase-by-phase growth and life cycle stability characterization (I & MR Chart).
3. All functional responses and design characteristics (X) that support a functional response (Y) are capable, typically with targets of Cp = 2 and Cpk = 1.5 (Capability Study).

The table below illustrates a tiered structure of % Knowledge-In-Hand to rate the risk a NUD Function or Characteristic is carrying due to the current level of capability documentation.

During the development of NUD parametric knowledge, one of the most effective leading indicators that show you are on plan and learning at a prescribed rate per the 12 Steps (see QG2) and the Project Schedule is the CP Worksheet. This document enables the CP Development Team to enter all candidate CP's as Ys and their controlling Xs for each high risk NUD Function under evaluation. Once the worksheet is loaded with the Ys and Xs, the System Engineer or Technical Leader responsible for CP documentation and the construction of the Design Guide enters % Knowledge-in-Hand (%KIH) values based on the guidelines presented in the Quick Guides 16 - 22 for each of The Big 7 Metrics. Note these are suggestions based upon common tools.

The following lists the column headers for the CP worksheet, which can be implemented using Excel. The first 9 columns define the functions and development information for the candidate critical Y's and X's.

1. Primary Function
2. Sub-Function
3. NUD or ECO Status of Function
4. NUD Priority #
5. Measured Y's
6. Y's Measurement Method & Units
7. Controllable X's
8. X's Measurement Method & Units
9. Design Controls* from DFMEA

*Design Controls are:

1. Computer-aided engineering (CAE)
2. Computer-aided design (CAD)
3. Characterization studies (regression)
4. Designed experiments (DOE)
5. Verification / Validation tests

The next 7 columns define and track the %KIH for candidate critical Y's and X's. % KIH is determined by application of the appropriate tools and methods for each Big 7 metric. The values for these columns are suggested in each of the Quick Guides 16 - 22.

10. Measurable (Y & X)
11. Stable (Y & X)
12. Adjustable (Y & X)
13. Independent / Interactive (X's)
14. Sensitive (deltaY / deltaX)
15. Robust (Y w/help from X)
16. Capable (Y & X)

The System Engineer or Technical Leader will partner with the Project Manager to determine when major tasks in the project schedule will produce data and new learning about the %KIH to be entered into the CP worksheet. The 12 Steps (see QG2) will indicate when specific tasks and tools are applied to generate the data and knowledge to mature your KIH. If your KIH is not progressing as planned, this indicates a problem with learning. Whatever the root-cause of the lack of progress must be corrected or the project is in jeopardy of not meeting its technical requirements. It is possible to gain 100% KIH and learn that the design being developed is incapable of meeting project requirements. KIH is a strong indicator of risk. If it is too low, then contingent action must be taken.

There are 24 Critical Parameter Development & Management (CPD&M) Quick Guides being published in installments in this newsletter. Below are links to each of the prior newsletters with CPD&M Quick Guides: 

The CPD&M Quick Guide TOC (Nov 2013)

CPD&M QG1&2: Intro & Process (Jan 2014) 

QG3&4: Prioritize Req'ts & Design Guide (Feb 2014)

QG5&6: Functional Diagramming & Functions, Complexity & Risk (Mar 2014)

QG7&8: Fn's, Design Controls, DG O'view & I-O-C Diagrams (Apr 2014)
*Note: there was no May 2014 issue

QG9: Design Failure Modes & Effects Analysis (DFMEA) (June 2014)

QG10&11: Fishbone & Noise Diagrams (July 2014)

QG12&13: Base-line & Robust P Diagrams (Aug 2014)

QG14&15: Robust Design P Diagrams & Big 7 Metrics O'view (Sep 2014)

QG16&17: Measurability & Stability (Metrics 1&2 of 7) (Oct 2014)

QG18&19: Adjustability & Independence, Interactivity & Stat. Sig. (Metrics 3&4 of 7) (Nov 2014)

QG20&21: Hypersensitivity & Robustness (Metrics 5&6 of 7) (Jan 2015)