Exam CTAL-TA_V4.0 Topic 1 Question 14 Discussion
Actual exam question for ISQI's CTAL-TA_V4.0 exam
Question #: 14
Topic #: 1
Question #: 14
Topic #: 1
You are working on a project to build a purchasing system. The main requirements for the system are that it shall:
* Allow users to enter details of items that they wish to have purchased and, from these details, create a purchase request.
* Take each purchase request through a workflow that will allow the requestor's line manager to approve the request, reject it or return it for clarification / modification.
* Forward approved requests to the Purchasing Department.
* Allow purchasers to find the best available supplier for each approved request and place the request on that supplier as a purchase order.
The solution is being developed according to the company's traditional V-model methodology. The requirements are clearly documented and include a business process model.
The main release has now been live for three months and you are working on the first maintenance release.
The test manager has asked you, the senior TA, to identify those parts of the test process which were most and least effective at finding defects in the main release.
You have collected statistics for the independent test activities, i.e. excluding developers' testing, including only the 178 defects in the three highest of your five defect severity levels. The results are presented in the table below:
Assume that all defects not found at the first opportunity could have been, e.g. that all defects that escaped into acceptance testing were within the scope and objectives of system testing. By applying Defect detection percentage (DDP) analysis, which test activity was LEAST effective?
* Allow users to enter details of items that they wish to have purchased and, from these details, create a purchase request.
* Take each purchase request through a workflow that will allow the requestor's line manager to approve the request, reject it or return it for clarification / modification.
* Forward approved requests to the Purchasing Department.
* Allow purchasers to find the best available supplier for each approved request and place the request on that supplier as a purchase order.
The solution is being developed according to the company's traditional V-model methodology. The requirements are clearly documented and include a business process model.
The main release has now been live for three months and you are working on the first maintenance release.
The test manager has asked you, the senior TA, to identify those parts of the test process which were most and least effective at finding defects in the main release.
You have collected statistics for the independent test activities, i.e. excluding developers' testing, including only the 178 defects in the three highest of your five defect severity levels. The results are presented in the table below:
Assume that all defects not found at the first opportunity could have been, e.g. that all defects that escaped into acceptance testing were within the scope and objectives of system testing. By applying Defect detection percentage (DDP) analysis, which test activity was LEAST effective?
Suggested Answer: B Vote an answer
The correct answer is B . CTAL-TA v4.0 explains that Defect Detection Percentage is used to evaluate how effectively a test level or activity detects defects, and a low DDP indicates a high percentage of escaped defects, meaning the activity was ineffective and should be analyzed for improvement. The official CTAL-TA sample-answer material gives the formula as DDP = D / (D + E) , where D is defects detected in that phase and E is defects that escaped that phase and were detected later.
For test analysis including requirements review , only requirements defects are in scope at the first opportunity. It found 13 requirements defects, while 52 requirements defects escaped and were found later: 12 in test design, 20 in system testing, 10 in acceptance testing, and 10 in live operation. Therefore, DDP = 13 / (13 + 52) = 13 / 65 = 20% .
For comparison, test design found 40 of the 100 defects it could have found, so DDP = 40% . System testing found 75 of 125 possible remaining defects, so DDP = 60% . Acceptance testing found 25 of 50 possible remaining defects, so DDP = 50% . The lowest DDP is therefore test analysis, including requirements review . Reference: CTAL-TA v4.0, Section 5.3.1 Analyzing Test Results to Improve Defect Detection .
For test analysis including requirements review , only requirements defects are in scope at the first opportunity. It found 13 requirements defects, while 52 requirements defects escaped and were found later: 12 in test design, 20 in system testing, 10 in acceptance testing, and 10 in live operation. Therefore, DDP = 13 / (13 + 52) = 13 / 65 = 20% .
For comparison, test design found 40 of the 100 defects it could have found, so DDP = 40% . System testing found 75 of 125 possible remaining defects, so DDP = 60% . Acceptance testing found 25 of 50 possible remaining defects, so DDP = 50% . The lowest DDP is therefore test analysis, including requirements review . Reference: CTAL-TA v4.0, Section 5.3.1 Analyzing Test Results to Improve Defect Detection .
by Tyler at Sep 06, 2026, 12:24 PM
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