Most Scrum teams estimate their top priority stories, select those stories that add up to their historical velocity for their sprint backlog. Some teams simplify this by merely counting the stories, or using the mathematical reciprocal, cycle time. Others make it more complicated, calculating the effect of days off and other known distractions from the work.
However they calculate it, some people put a lot of faith in the historical data to guide the future. “It’s data,” they say, “it’s better than guesses and not subject to cognitive bias.” Not all data is easily measured and converted to numbers, though. Limiting yourself to this initial calculation is, itself, an example of anchoring bias.
After planning the work for the next short interval of time, it’s helpful if a team looks each other in the eyes and asks themselves, “Can we do this much; could we do more?” If a group can’t do this and give itself an honest answer, it’s probably not yet a true team. A true team will be able to make a gut judgement of what the team as a whole can or cannot do. This judgement will take into account data that may not yet be identified and articulated, much less converted to numbers.
I’ve observed teams ask themselves this question and then get really quiet. No, they don’t feel they can do this work. Eventually someone speaks their doubt, and everyone else chimes in. They may identify reasons why this time period is different from the past. “There are a lot of distractions around the upcoming acquisition of another company.” They may identify reasons why this body of work is different from the past. “This is a new technology. We’ve investigated it, but never used it in production.” “Much of this work involves the skills of only one person. It’s going to be less efficient having others come up to speed on this work.” They may not identify the reasons at all, but still know in their hearts that their rational process is giving them the wrong answer.
Pay attention to that gut feel. It’s data, just as much as the numbers. Judgement is what turns data into choices. Making automatic decisions based on the numbers is an abdication of that judgement.