SFRA: SFRA bias in magnitude and phase

Part Number: SFRA

Tool/software:

Hi Experts,

My customer is observing bias (calculated value vs SFRA result) that the SFRA would have slightly smaller magnitude and more leading phase, this trend is common on one of the reference desgin and customer's own board.

Is this a common experience using SFRA or just a independent case?

Regards,

Hang