The traditional approach to estimation is based on team relative size estimates is backed by research. The approach has proven to improve outcomes associated with estimation, but that does not mean this is the only estimation approach we can use.

Alternative approaches include:

• #noestimates approaches: there is a lot discussion about this thinking and the discussion is worthwhile. See Do We Need Points To Generate a Release Burn-up Chart? for this type of thinking.
• Cycle time and throughput: More generally, using cycle time and throughput information directly can help.
• XP based: 0, 1, 2, 4, split. Used to help encourage smaller pieces of work.
• High / low estimates: The approaches generate a single number to estimate size of a Story. When forecasting the future we should be talking about a range of possible values rather than a single number as the future is not certain.
• Probabilities: A more rigorous approach is to use actual probabilities to talk about what might happen. See Why a Plan Based on Average Velocity Will Fail? for the thinking here.
• Dependencies: Estimation approaches that directly factor a understanding of dependencies to drive better information. See Why Should We Work Harder to Eliminate the Effect of Dependencies? for some thinking here.
• Expansion: Estimation approaches that also factor in expansion of scope, since in most cases scope increases rather than decreases, as the team implements and the customer sees what is possible.
• Utilization / WIP: Understanding the impact of high utilization on estimates. See Why Does a High Utilization Rate Make It Impossible to Create Good Estimates? for more information.

Organizations can and should improving their process to so that they produce the least amount of wasted effort in return for the information gained.

• Why Do We Use Story Points Instead of Hours or Days?
• What is the Purpose of Estimation?