The Fnorm response amplitude depends on the measured On-time as well as on the selected on-time for analysis (see Response Evaluation Mode). The area response on the other hand only depends on the measured on-time. Higher amplitudes are expected usually for 5 sec measurements than for 3 sec measurements.
For Fnorm analysis the response amplitude can be negative or positive, depending on the exact influence of ligand binding on the target TRIC signal. The response amplitude will be negative if the TRIC signal of the complex is lower than that of the target alone, and positive if the TRIC signal of the complex is higher than that of target alone. Both directions are common and for evaluation the direction of the response amplitude is irrelevant.
Note: Also read the article on Response Quality to learn more about response amplitudes and their significance.