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106 Chapter 4 Requirements engineering

INITIAL ASSUMPTION:
The patient has seen a medical receptionist who has created a record in the system and collected the patient’s
personal information (name, address, age, etc.). A nurse is logged on to the system and is collecting medical history.
NORMAL:
The nurse searches for the patient by family name. If there is more than one patient with the same surname,
the given name (first name in English) and date of birth are used to identify the patient.
The nurse chooses the menu option to add medical history.
The nurse then follows a series of prompts from the system to enter information about consultations elsewhere
on mental health problems (free text input), existing medical conditions (nurse selects conditions from menu),
medication currently taken (selected from menu), allergies (free text), and home life (form).

WHAT CAN GO WRONG:
The patient’s record does not exist or cannot be found. The nurse should create a new record and record
personal information.
Patient conditions or medication are not entered in the menu. The nurse should choose the ‘other’ option and
enter free text describing the condition/medication.
Patient cannot/will not provide information on medical history. The nurse should enter free text recording the
patient’s inability/unwillingness to provide information. The system should print the standard exclusion form
stating that the lack of information may mean that treatment will be limited or delayed. This should be signed
and handed to the patient.

OTHER ACTIVITIES:
Record may be consulted but not edited by other staff while information is being entered.
SYSTEM STATE ON COMPLETION:
User is logged on. The patient record including medical history is entered in the database, a record is added to
the system log showing the start and end time of the session and the nurse involved.

Scenario-based elicitation involves working with stakeholders to identify scenar-
Figure 4.14 Scenario
for collecting medical ios and to capture details to be included in these scenarios. Scenarios may be written
history in MHC-PMS as text, supplemented by diagrams, screen shots, etc. Alternatively, a more structured
approach such as event scenarios or use cases may be used.
As an example of a simple text scenario, consider how the MHC-PMS may be
used to enter data for a new patient (Figure 4.14). When a new patient attends a
clinic, a new record is created by a medical receptionist and personal information
(name, age, etc.) is added to it. A nurse then interviews the patient and collects med-
ical history. The patient then has an initial consultation with a doctor who makes a
diagnosis and, if appropriate, recommends a course of treatment. The scenario
shows what happens when medical history is collected.

4.5.4 Use cases

Use cases are a requirements discovery technique that were first introduced in the
Objectory method (Jacobson et al., 1993). They have now become a fundamental
feature of the unified modeling language. In their simplest form, a use case identifies