I was reading about statistical filters, and I came across a sentence that I didn't understand:
You might be thinking that there's not much difference between 95 percent and 99.5 percent. But you would be wrong. A filter with a 99.5 percent accuracy rate is not merely 4.5 percent more effective than one that is 95 percent accurate, but 900 percent more effective!
Can someone explain how a filter that is 99.5 percent accurate is 900 percent more effective than 95 percent?