Estimates

Last updated Jun 5, 2023

Through estimation, we can find out how much work we have ahead of us.

Instead of trying to determine exactly how long a task will take, we compare the effort of that task to another task, and that becomes the estimate.

Methods:

• T-shirt sizes
• Story points

• The team picks a task that seems “medium” complex to complete; from now on, it will be the “Medium” size.
• The team compares the other items against the medium size and assigns Small, Extra Small, Large, and Extra Large complexities.

• The team picks a task that becomes the “anchor” item and will conduct estimates against it.
• The team uses the Fibonacci sequence to assign complexity to the other items.

• Check their understanding of the task.
• Ask for estimates of the Tasks and note them.
• Discuss the assumptions the expert might be making when they give you an estimate
• Ask the task expert to consider how likely it might be that the assumption might not work out and how that might impact their estimate
• Understand the different kinds of Estimations
• Compare the expert’s estimates against the actual time spent on similar tasks in previous work.

It is used to help determine the most realistic time estimate for a task. It uses optimistic and pessimistic calculations, meaning calculations based on the best-case and the worst-case scenarios.

• Each task receives three estimates:
  • Optimistic
    • Assume the best-case scenario, that issue will not occur
  • Most-Likely
    • Assume some issue might occur and is based on how long the task usually takes under normal circumstances
  • Pessimistic
    • Assumes the worst-case scenario, that issue will definitely occur
• Each estimate indicates the amount of time a task will take under that category

The weight of each estimate in this equation is identical, which means the most likely case does not affect the final estimate more than the optimistic or pessimistic estimates.

E = (o + m + p) / 3

The Beta (PERT) distribution is a weighted average. The most likely estimate receives a multiplier of four, while the overall divisor is increased to six.

This method takes into account that the most likely case is more likely to occur, so it’s given more weight. The added weight is reflected in the multiplier of four.

E = (o + 4m + p) / 6

Indicates how confident you are in an estimate’s accuracy.

• Use the [](None#Three-point estimating) technique
• Poll your team
  • Get a percentage for how confident they are
  • Define categories for the team
    • like “we did it in the past” or “we never did it” and associate a confidence to each category.