Develop a dependency hierarchy for “Key Factors” – Y-measures, products and services (that a Six Sigma DFSS or DMAIC project can create or improve), and X-factors.
For example, during MEASURE, discern the extent to which some X-factors depend on other X-factors.
1. Review an introduction to GIST. Read pages 7-9, 11, and 15 in the book GIST: Gain Impact. Save Time. (See reference  below.)
2. Review GIST’s Select Service tool. Read pages 22-23.
Do the following.
1. Focus on 1 definition of “the customer” and on 1 definition of “a customer endeavor.” For example, …
1.1 List key customers for a product or service that the DFSS or DMAIC project seeks to create or improve.
1.2 For each key customer, describe in customer-centric terms at least one endeavor in which the customer can benefit from the product or service. Consider choosing endeavors broader in scope than just “the customer uses the product or service.” For example, consider selecting endeavors for which the customer’s use of the product or service represents one of several steps.
1.3 Characterize a composite customer and then a representative endeavor.
2. Recall or generate a list of Key Factors. For example, to generate Key Factors, use the technique “The GIST of Identifying Potential Causes (X-Factors).” (See reference  below.)
3. Catalog Key Factors.
3.1 Consider the product or service to be the “provider.” Consider the composite customer to be the “client.” (See Figure 1, page 8.) Consider the above-selected endeavor to be the “endeavor” to use with the template specified below.
3.2 Use the Select Service template. (See Figure 13, page 22.) Associate each Key Factor with one of 6 categories in the template. If more than 1 category seems to apply to a Key Factor, consider developing more-specific “child” Key Factors, with each falling into 1 category; then, consider ignoring the “parent” Key Factor.
4. Recognize dependencies between Key Factors. Generally, Key Factors in closer-to-Outcomes categories set requirements for and depend on support from Key Factors in farther-from-Outcomes categories.
This technique was developed by Thomas. J. Buckholtz. (See reference  below.)
 Buckholtz, Thomas J., GIST: Gain Impact. Save Time., 2006. Available as an e-book via Tom’s books . GIST provides a systems-thinking tool set for pinpointing, communicating, and achieving pivotal “who, what, why, when, how, …” for outcomes, products, services, organizations, teams, relationships, and communication.