Subjective testing mainly depends on an expert's opinion. An expert is a person who is proficient and experienced in the system under test. Conducting the test involves test runs of the simulation by the expert and then the expert evaluates and validates the results based on some criteria.

One advantage of this approach over objective testing is that it can test those conditions which cannot be tested objectively. For example, an expert can determine whether the joystick handling of the flight feels "right".

One disadvantage is that the evaluation of the system is based on the "expert's" opinion, which may differ from expert to expert. Also, if the system is very large then it is bound to have many experts. Each expert may view it differently and can give conflicting opinions. This makes it difficult to determine the validity of the system. Despite all these disadvantages, subjective testing is necessary for testing systems with human interaction.