Then, the paper presents the develop trend about the comprehensive estimation of fracture rock, study on dynamic model and numerical modelling, and combining the theory with practice.

Results there is multi-collinearity bias in the result of the least square estimation trend-surface model, use the method of ridge regression can control the multi-collinearity bias.

Passive surveillance system, because of too high missing report rate, is not suitable to be used to estimate the incidence and only can be use for the estimation of epidemic trend.