ITPEC FE Morning October 2018 Question 55
ITPEC FE Morning October 2018 — Question 55 of 80
Bug Convergence Curve — recognizing when software quality is stabilizing during testing
The correct answer is d).
A cumulative bug chart plots the total number of discovered bugs against the number of completed test items. Quality is considered stable when this curve flattens into a plateau — meaning new tests are finding fewer and fewer bugs.
- •a) Curve accelerates upward — bugs are being found at an increasing rate, indicating poor quality and possibly more latent defects.
- •b) Curve goes up then decreases — impossible for a cumulative count (totals never go down).
- •c) Straight diagonal line — bugs are found at a constant rate with no sign of convergence. Testing has not yet stabilized quality.
- •d) ✅ S-shaped curve that levels off — initially bugs are found frequently, then the rate slows and the curve plateaus. This is the classic reliability growth curve indicating quality convergence.
Why not others:
- (a) shows worsening quality, (b) is mathematically invalid for cumulative data, and (c) shows no convergence trend.
Key rule: A plateau in the cumulative bug curve = bug detection rate → 0 = quality is stabilizing. This is the signal that testing can be concluded.
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