In Jelinski-Moranda SRGM, what does N0 represent?

• A. The initial number of latent defects (unobserved)
• B. The initial observed failures
• C. The total time of testing
• D. The test environment temperature

Answer: (A)

In Jelinski-Moranda SRGM, the number N0 is the initial number of latent defects in the software before testing begins. Latent defects are problems that exist but have not yet caused a failure, so they’re unobserved at the start. The model links the failure rate to how many latent defects remain: as testing uncovers and fixes defects, the pool of remaining latent defects shrinks, causing the observed failure rate to drop over time. N0 is a starting count for that latent pool and is treated as a parameter to be estimated from failure data. It is not the number of observed failures, nor the total testing time, nor an environmental variable such as temperature.