Limited Requirements, Unpredictable Variables and Lack of Historical Project Data all Contribute to Challenges in Project Estimating
User Story (Agile) & Use Case (Traditional) templates are provided below article with resulting estimates.
Many organizations may not have a formal lessons learned project database containing historical project data of similar types. Many project managers find themselves in a situation where they are required to build a project schedule and need task estimating techniques that are more accurate than top-down estimates and can be completed relatively quickly. T-Shirt Size and Planning Poker are two common estimating techniques practiced in Agile that can also be used in Waterfall and hybrid project environments. The PERT formula can be applied to these estimates to arrive at realistic numbers between pessimistic and optimistic. Both methods have their own strengths and weaknesses, making them suitable for different contexts and team dynamics. This article explores how to use these techniques, their pros and cons, and when to apply them.
Categorizing Measurement Units – Hours, Days, Weeks or Months
Keep it simple when estimating and use measurement units of hours, days, weeks or months. The article image at the top can be a reference point in setting up units of measurement for estimating by project teams.
T-Shirt Size Estimation
How to Use T-Shirt Size Estimation
T-Shirt Size estimation is a relative estimation technique that categorizes tasks or user stories into sizes resembling clothing sizes: XS (Extra Small), S (Small), M (Medium), L (Large), and XL (Extra Large). Here’s how to implement it:
- Gather the Team: Assemble the team members who will be involved in the project. This should include developers, testers, and any other relevant stakeholders.
- Define the User Stories (Use Cases in Waterfall): Clearly outline the user stories or tasks that need to be estimated. Ensure that all team members understand the requirements.
- Discuss and Clarify: Allow team members to discuss each user story. This discussion helps clarify any ambiguities and aligns the team on the scope of the task.
- Assign Sizes: After discussion, each team member assigns a T-shirt size to the user story based on their understanding. This can be done openly or anonymously, depending on the team’s preference.
- Reach Consensus: If there are significant discrepancies in the assigned sizes, facilitate a discussion to understand the differing perspectives and reach a consensus.
Pros and Cons of T-Shirt Size Estimation
Pros:
- Simplicity: The T-Shirt Size technique is easy to understand and implement, making it accessible for teams new to Agile.
- Quick Estimation: It allows for rapid estimation of user stories without getting bogged down in detailed analysis.
- Relative Sizing: By using relative sizes, teams can quickly gauge the complexity of tasks compared to one another.
Cons:
- Lack of Precision: The broad categories can lead to ambiguity, making it difficult to derive precise time estimates from T-shirt sizes.
- Subjectivity: Different team members may have varying interpretations of what each size means, leading to inconsistencies.
- Limited Detail: This method does not account for specific complexities or dependencies that might affect the actual effort required.
When to Use T-Shirt Size Estimation
T-Shirt Size estimation is best used in the early phases of a project when the team is still gathering requirements and exploring the overall scope. It is particularly useful for high-level planning and when trying to quickly assess the size of multiple user stories without getting into detailed discussions.
Planning Poker
How to Use Planning Poker
Planning Poker is a consensus-based estimation technique that uses a deck of cards with values representing effort or complexity. It is recommended that Fibonacci numbers of: 1, 2, 3, 5, 8, 13, 20, 40, 100 – zero and 1/2 may also be used. The Fibonacci numbers represents level of effort or amount of time. The Fibonacci sequence grows non-linearly, which reflects the increasing uncertainty and complexity associated with larger tasks. As the size of the task increases, the uncertainty also tends to increase, and using a non-linear scale helps teams account for this. Here’s how to implement it:
- Gather the Team: Similar to T-Shirt Size estimation, bring together the relevant team members.
- Present User Stories: Clearly present the user stories or tasks that need to be estimated.
- Discuss Each Story: Allow time for discussion, ensuring that all team members understand the story’s requirements and any potential challenges.
- Estimate Using Cards: Each team member selects a card that represents their estimate for the user story (use case). All cards are revealed simultaneously to avoid influencing each other’s estimates.
- Discuss Discrepancies: If there are significant differences in estimates, facilitate a discussion where team members explain their reasoning. This helps uncover hidden complexities or assumptions.
- Re-estimate if Necessary: After discussion, the team can re-estimate the user story, repeating the process until a consensus is reached.
Pros and Cons of Planning Poker
Pros:
- Encourages Participation: Planning Poker promotes equal participation from all team members, ensuring diverse perspectives are considered.
- Facilitates Discussion: The technique encourages discussion about user stories, leading to a better understanding of requirements and potential challenges.
- Reduces Anchoring: By revealing estimates simultaneously, it minimizes the risk of anchoring bias, where one person’s estimate influences others.
Cons:
- Time-Consuming: The process can be time-consuming, especially for larger user stories or complex projects where extensive discussion is needed.
- Requires Familiarity: Team members need to be familiar with the Fibonacci sequence and the concept of relative estimation, which may require training.
- Potential for Groupthink: While the technique encourages discussion, there is a risk of groupthink if dominant personalities influence the consensus.
When to Use Planning Poker
Planning Poker is particularly effective for teams that have established a level of Agile familiarity but with some practice can be used by Waterfall and Hybrid teams that are looking for a more structured and collaborative estimation process. It is best used when estimating user stories (or use cases) that are well-defined and require detailed discussion to uncover complexities.
Choosing Estimation Techniques
Both T-Shirt Size and Planning Poker are valuable estimation techniques in Agile project management and I find them very applicable in Waterfall or Hybrid projects. T-Shirt Size is best for quick, high-level estimates, while Planning Poker is more suitable for detailed discussions and consensus-building. By understanding the strengths and weaknesses of each method, teams can choose the right approach based on their specific context and project needs, ultimately leading to more accurate and effective planning.
Below are User Story & Use Case templates that are completed after task estimates are determined by the project team.