What are the relationships between requirements?

There are several types of relationships between requirements; it helps to know and understand these relationships in order to determine the most appropriate traceability approach for your specific project situation and traceability needs.

Let's consider the following example to explain these relationships further:

 A bank is required to build an online loan application solution. 

These relationships are as follows: 

• Derive – An applicant would need to log in to the bank's online system to use the online loan application solution. The information required to validate whether the user is a valid and registered user of this system is derived from the login process. 
• Depends – For an applicant to be able to complete a loan application form, the applicant would need to be logged in and validated on the bank's online system. Thus, the completion of the form requirement is dependent on the login and validation requirements process.

There are two further types of dependency relationships to consider in this example: 

• • Necessity – It is required to now also add new database fields to the bank's existing database to hold user online registration details. Without this data, it will be impossible for the validation process to function and is thus a necessity.
  • Effort – It will most likely be easier to implement all file changes at the same time, seeing that some changes to a specific file or table are currently required, but because future fields on the same tables are envisaged, it will be less effort to implement all file changes at the same time.

• Satisfy – Has the implemented solution satisfied the need to allow an applicant to complete an online application securely, according to the company standards, for example?  
• Validate – Has the requirement successfully been validated against the test case?

As a business analyst, you should, therefore, consider the purpose of each of these types of traceability relationships prior to finalizing the traceability approach that you will be implementing for your project.