Game Development Reference
results, take a good hard look at what changes you can make to avoid a repeat perfor-
mance. You can start by going through the list of non-conformances that QA found
during the project.
Phase containment is the ability to detect faults in the project phase in which they
were introduced. Phase Containment Effectiveness (PCE) is a measure of how well
that is being done.
Faults that are found in the phase in which they are introduced are known as in-phase
faults or “errors.�? Faults that don't get caught in the same phase in which they are
introduced are said to escape and become “defects.�? The principle is that if any subse-
quent work is derived from the faulty item, then a defect has occurred. Think of the
18" Stonehenge descending from the ceiling in the movie Spinal Tap . That could have
been avoided (but not as funny…) if someone noticed the size was given in inches
instead of feet on the drawing given to the artist.
Errors are typically found by reviews, walkthroughs, or inspections. Defects are most
noticeably found by testing and unhappy customers, but they can also be found in
reviews of downstream work products. For example, a code inspection issue might
actually be the result of incorrect design or requirements. Because other work has
already been done based on the fault, this is a defect.
PCE is typically tracked and reported by showing the faults found in each develop-
ment phase. The faults are organized into columns for each phase in which they might
be found. A coding fault can't be detected in the requirements phase because the code
does not exist at that point. Calculate PCE by dividing the number of in-phase faults
by the sum of faults found in all phases to come up with the PCE for that phase. From
the data in Figure 6.2, the design phase PCE is calculated by dividing the number of
faults found in the coding phase, 93, by the sum of all faults introduced by coding,
which is 93 + 6 + 24 = 123. The result is 93/123 = 0.76. Figure 6.3 shows a graph sum-
marizing the code PCEs for each phase.
Figure 6.2 Game code phase containment data.