Prudence analysis (PA) is a relatively new, practical and highly innovative approach to solving the
problem of brittleness in knowledge based system (KBS) development. PA is essentially an online
validation approach where as each situation or case is presented to the KBS for inferencing the result
is simultaneously validated. Therefore, instead of the system simply providing a conclusion, it also provides
a warning when the validation fails. Previous studies have shown that a modification to multiple
classification ripple-down rules (MCRDR) referred to as rated MCRDR (RM) has been able to achieve
strong and flexible results in simulated domains with artificial data sets. This paper presents a study into
the effectiveness of RM in an eHealth document monitoring and classification domain using human
expertise. Additionally, this paper also investigates what affect PA has when the KBS developer relied
entirely on the warnings for maintenance. Results indicate that the system is surprisingly robust even
when warning accuracy is allowed to drop quite low. This study of a previously little touched area
provides a strong indication of the potential for future knowledge based system development