Due to aggressive technology downscaling, mobile and embedded systems are susceptible to transient faults in the underlying hardware. Transient faults may incur soft-errors or even lead to system failure. A recent study has proposed to exploit the concept of the (m,k)-firm real-time task model with compensation techniques to manage redundant executions, aiming to selectively protect the control application. In this work we provide an empirical approach to find the (m,k) robustness requirements. With the delivered (m,k) robustness requirements on path tracing and balance control tasks, we conduct comprehensive case studies to evaluate the effectiveness of the compensation techniques under different fault locations and fault rates.