Why is the modified Fibonacci sequence used when estimating?

Question

Options

• AIt serves as a way to estimate large ranges
• BIt can be used to predict unit test coverage
• CIt results in greater precision
• DIt reflects the uncertainty in estimating larger items

• A
  6% (2)
• B
  3% (1)
• C
  3% (1)
• D
  88% (29)

Explanation

Option D is correct because the modified Fibonacci sequence (1, 2, 3, 5, 8, 13, 20, 40, 100...) has intentionally increasing gaps between values as numbers grow larger, which mirrors how human estimation ability degrades with complexity - we can reliably distinguish a 2-point story from a 3-point story, but not a 42-point story from a 45-point story, so those granular distinctions are removed entirely.

Why the distractors are wrong:

• A is partially true in effect but misses the why - the sequence doesn't exist to handle large ranges as a goal; that's a byproduct of modeling uncertainty.
• B is fabricated - story point sequences have no relationship to unit test coverage prediction.
• C is the opposite of the truth; the modified Fibonacci sequence deliberately reduces precision at higher values to avoid false confidence.

Memory tip: Think "fuzzy at the top" - the bigger the item, the fuzzier our estimate, and the Fibonacci gaps grow to match that fuzziness. If the sequence gave you equal precision at 100 as at 2, that would be lying to the team.

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