Final answer:
The statement is false; database structures are defined during the design phase, not typically changed during implementation, although minor unforeseen adjustments might occur.
Step-by-step explanation:
The statement that characteristics of the structure of the database are generally changed during the implementation phase of the database development process is false. Typically, the structure of the database is defined during the design phase. The implementation phase is where the database is actually created based on the design specifications. It is during the design phase where the data model is refined and set, not during implementation. However, some minor changes might occur during implementation due to unforeseen technical issues, but these changes are generally avoided because they can be expensive and time-consuming to correct.