Can Six Sigma Work in a Sales and Marketing Environment? by Paul Selden:

Sales is often an area that is treated as though it were separate from the company. That leads to all sorts of problems. Sales needs to be seen as part of the system of the organization and managed in that way. Just remember systemic thinking (viewing the entire system) will be needed, not just analysis (viewing the components of a system).

Related: Marketers Are Embracing Statistical Design of Experiments - Appeal for Marketers to Apply Deming’s Ideas - Marketing in a Lean Company - Problems with Bonuses - Free, Perfect, and Now (book by Robert Rodin) - Design of Experiments explanation