The SATC has currently examined and modeled error data from a limited number
of projects. Generally, only the date on which an error was entered into the
error tracking system was available, not the date of discovery of the error. No
useful data was available on human or computer resources expended for testing.
What is needed for the most accurate model is the total time expended for
testing, even if the times are approximate. Using the sum of reported times to
find/fix individual errors did not produce any reasonable correlation with the
resource function required. Some indirect attempts to estimate resource usage,
however, led to some very good fits.
On one project errors were reported along
with the name of the person that found the error. Resource usage for testing was
estimated as follows: A person was estimated to be working on the testing effort
over a period beginning with the first error that they reported and ending with
the last error that they reported. The percentage of time that each person
worked during that period was assumed to be an unknown constant that did not
differ from person to person. Using this technique led to a resource curve that
closely resembled the Rayleigh curve (Figure 1).
