Explain why this estimate should be adjusted to take project, personnel, product and organizational factors into account. Suggest four factors that might have significant effects on the initial COCOMO estimate and propose possible values for these factors. Justify why you have included each factor.

Question

A software manager is in charge of the development of a safety-critical
software system, which is designed to control a radiotherapy machine to
treat patients suffering from cancer. This system is embedded in the
machine and must run on a special-purpose processor with a fixed amount
of memory (256 Mbytes). The machine communicates with a patient
database system to obtain the details of the patient and, after treatment,
automatically records the radiation dose delivered and other treatment
details in the database.
The COCOMO method is used to estimate the effort required to develop this
system and an estimate of 26 person-months is computed. All cost driver
multipliers were set to 1 when making this estimate.

Answer 1

It is adjusted because the time and effort required to complete a project depends on
various factors such as the experience of the development team, the development
schedule, the support facilities etc.
In this case, they have to go back to the system description and recognise
the factors which might add to the difficulty (and hence the cost) of implementing
the system. For example:
• Safety-criticality
• Memory limitations on system
• External interfaces with DBMS
• Unusual hardware (‘special-purpose processor)