Six Sigma is a Total Quality Management (TQM) method for reducing defects and, additionally, increasing the quality of a product. I am definitely not a Black Belt Six Sigma Practitioner, nor actually any Belt. (They have evocative titles for their practitioners.) I am familiar with the methodology through clients who have been engaged in Six Sigma Voice of the Customer projects. Voice of the Customer (VOC) is a Six Sigma process for gathering user input for product design, mainly through surveys, focus groups, and feedback channels. There are critics who muse that VOC might restrict the creativity of product design teams, but that is another discussion. I have seen VOC used to assess customer satisfaction–a technique somewhat related to usability testing the product, foregoing the process of observation in lieu of gathering self-reported usability data. If an organization has participated in a VOC project, then they are likely to possess willingness to reach out to customers. This can be an asset when you set out to create a mental model. Organizations that do not have this experience may have to overcome a natural reluctance to reach out and contact users. The difference between VOC and the mental model technique is that you will be getting to know the customer in a deeper way.