Estimation Techniques

Ratio-based

Test team’s are typically given a percentage of of the total development time, based on historical data.

Assumes that the complexity and scope of the new project is similar to previous projects.

Extrapolation

Typically in agile/scrum, the time estimated for feature development is based on the development time of similar features in previous sprints of similar size and complexity.

It’s an educated guess based on historical data.

EXAM
Given an estimation scenario, answer which technique is being used.

Wide band Delphi

Panel of experts (e.g. engineers, designers, and product managers) that have done similar work before.

Each expert makes an initial guess, followed by a round of feedback and discussions until a consensus is reached on effort and time.

Three-point estimation

• Optimistic (O)
• Pessimistic (P)
• Most likely (M)

Estimated Time (E) = (O + 4M + P)/6 Standard Deviation (SD) = (P - O)/6

E.g, if O=120, M=150, P=200

E = (120 + 4150 + 200)/6 = 153.3 SD = (200 - 120)/6 Calculated estimated time = 153 +/- 13.33

*EXAM Memorize these formulas