A simulation is performed using a digital space reproduced based on a real space in which a service is provided. Based on a simulation result satisfying a predetermined convergence condition, a threshold for detecting occurrence of an abnormality in one or more works performed in association with provision of the service in the real space may be set for each work unit corresponding to the one or more works. When the threshold is set, the time difference between the preset standard working time and the simulated work time included in the simulation result satisfying the convergent condition is calculated. A larger threshold value is assigned to a work unit having a larger time difference than a work unit having a smaller time difference.