Time Series Root Cause Surprise Score

Surprise score is used to capture the relative change for the root cause item. $$S_i(m) = 0.5( p_i\log_2(\frac{2p_i} {p_i+q_i}) + q_i \log_2(\frac{2q_i}{p_i+q_i}) )$$ $$p_i(m)= \frac{F_i(m)} {F(m)} $$ $$q_i(m)= \frac{A_i(m)} {A(m)} $$ where $F_i$ is the forecasted value for root cause item $i$, $A_i$ is the actual value for root cause item $i$, $F$ is the forecasted value for the anomly point and $A$ is the actual value for anomaly point. For details of the surprise score, refer to this document