In this chapter, we learned that the product backlog must include only those feature ideas that will have a significant impact on Key Business Outcomes. If a feature idea is not expected to meet Key Business Outcomes, then there is no value in spending any effort in exploring the idea. Effort here is analysis, viability testing, market research, and so on. Needless to say, we need data and insights to make a better estimate about the impact of a feature idea, but sifting through this ensures that our product backlog stays lean. We can then steer all our efforts toward the most valuable outcomes, both for the customer and for the business. Impact scores are only one aspect of determining the effectiveness of a feature. There are costs associated with implementing a feature idea.

Before we venture into the costs of building a feature, we need to define success criteria. We must define what indicators will tell us not just if our estimated value impact is correct, but also where we failed to find success. What makes us happy? Is it user experience? Is it how quickly users can access our content? Is it the quality of our content? Is it the lack of complaints about mismatched content? Let's find out more about defining success criteria in the next chapter.