Defect Density

Correct Answer: The overtime may lead to tiredness and increase in errors, thereby increasing Defect Density

The increasing defect density in a project even when developers are working overtime could be primarily due to the fatigue of the developers. In such situations, the team often experiences burnout and makes more errors, which results in a high Defect Density. Therefore, 'The overtime may lead to tiredness and increase in errors, thereby increasing Defect Density' is the most probable reason. The other possible reasons provided are: 'The team is under-staffed', 'The team is not qualified' and 'The project is not managed properly'. However, without additional information, it's hard to definitively say that these are the causes. An under-staffed team or a poorly managed project could indeed result in increased Defect Density, but these factors can also cause other issues apart from an increasing Defect Density. As for the qualification of the team, while it's important, it is not directly linked to Defect Density – a qualified team can still make mistakes if they are overworked.

Correct Answer: The code review practice is effective as it has led to a decrease in Defect Density

The best answer is 'The code review practice is effective as it has led to a decrease in Defect Density'. Defect Density is a metric used to show the efficiency of a development process - the lower the number, the fewer defects there are per unit of code. A decrease from 70 to 50 means that there are fewer defects in the code, indicating that the code review practice is effective. The answer 'The code review practice is slowing down the development process' is incorrect because it doesn't relate to the changes in Defect Density. The comment 'The code review practice has no real impact' is also wrong as the substantial decrease in Defect Density indicates that the new practice does have an impact. Finally, 'The code review practice is ineffective, that's why Defect Density has decreased' is incorrect because a decrease in Defect Density means the practice is working, not failing.

Correct Answer: More defects have been found than those have been fixed

The increase in Defect Density despite the increase in defect fixing implies that more defects are being identified than the ones being fixed. This is because Defect Density is a metric that represents the number of defects identified in the product divided by the size of the product. Hence, even if defect fixing increases, if the number of defects found increases more proportionally, then the Defect Density would not decrease. Now, let's look at the other options. The option 'There are no defects, the measurement is incorrect' might not be the case as the question says 'despite an increase in defect fixing' which implies there are indeed defects. The option 'The testing team is not working properly' lacks context and is speculative and 'The Fixed defects have reappeared' although could be a possibility, it's not the most probable one, as usually after a bug is fixed and tested, it's unlikely to reappear, and if it does then it's an indication of bad practices which is not indicated in the question.