01 Clayton, M. C., & Raynor, M. E. (2003). The Innovator’s Solution: Creating and Sustaining Successful Growth. Harvard Business School Press.
02 Noble, C. (2011). Clay Christensen’s Milkshake Marketing. Harvard Business School Working Knowledge.
Jobs to be done (JTBD) is another way to formulate insights. Originally named by Clayton Christensen from the Harvard Business School, JTBD provides a valuable perspective with regard to innovation.  The “job to be done” describes what a product helps the customer to achieve. Looking for the JTBD is a method to move away from the current solution and create a new frame of reference for a different future solution. The JTBD framework includes a social, a functional, and an emotional dimension.
Sometimes an additional starting line can be added when you have at least two distinct jobs for the same situation: “As … (persona/role), when …” However, JTBD is mostly used without a persona or role. Clayton Christensen explains the jobs-to-be-done framework with his classic milkshake example:  he investigates the question “Why are half of all milkshakes at a fast food brand sold before 8 a.m.?” Based on iterative ethnographic research (short observations and interviews), the research team realized that customers were trying to accomplish a very specific job and this is why they “hired a milkshake.” Clayton formulates the job story somewhat like this: “When I am commuting to work by car, I want to eat something that I can get quickly and that doesn’t distract me from driving, so that I can work until lunch without feeling hungry.”
The reason customers buy a milkshake instead of a banana, a doughnut, a bagel, a chocolate bar, or a coffee is because they need something easy to eat that will keep them full until lunch. In this example, from a customer’s perspective, competitors are not other fast food chains, but rather alternatives that would do a similar job for them, like a smoothie, for example.
A JTBD insight based on this framework is quite similar to a key insight – the main difference is that a key insight focuses on the restriction/friction/problem, whereas a JTBD focuses more on the larger picture of the situational context and motivation. One of the key advantages of the JTBD approach is that it helps a design team break away from a current solution in order to discover new solutions based on what customers really want to achieve.