Also, one would assume that the TSP process was developed while
keeping the Phase Delay effect in mind. That might be one cause why
the effect is not predominantly seen in the projects studied, that
point is not mentioned in the paper anywhere. One independent metric
would have been to study some loosely developed projects and see if
the effect is seen. The authors themselves pointed out that "The
time in final testing is particularly low suggesting that few
defects survived into testing". So, no major defect might have
survived long enough in the system.
Also, one would assume that the TSP process was developed while keeping the Phase Delay effect in mind. That might be one cause why the effect is not predominantly seen in the projects studied, that point is not mentioned in the paper anywhere. One independent metric would have been to study some loosely developed projects and see if the effect is seen. The authors themselves pointed out that "The time in final testing is particularly low suggesting that few defects survived into testing". So, no major defect might have survived long enough in the system.