We launched a new fraud rule last month. It blocked 500 transactions, and after investigation only 50 of them turned out to be real fraud. In the same month there were 200 fraudulent transactions in total. How would you evaluate this rule?

风控上了一条新的欺诈规则，上个月它拦下了500笔交易，事后核实其中只有50笔是真欺诈；同期全部欺诈交易一共200笔。你觉得这条规则效果怎么样？