that simple circular out what they are stating is that there's a 90% reported evidence of something being found. does that mean there was not evidence found. that leads to the next kind of obvious follow—up question. if it is so difficult to work out whether a shot has actually been fired on the ground how does shot spotter know with such confidence that it's 97% accurate? shot spotter told the bbc it works out its accuracy from police reports on the ground listening to gunshots, telling shot spotter when they got it wrong. we telling shot spotter when they got it wronu. ~ , ., ., it wrong. we rely on ground truth from agencies — it wrong. we rely on ground truth from agencies to _ it wrong. we rely on ground truth from agencies to tell _ it wrong. we rely on ground truth from agencies to tell us - it wrong. we rely on ground truth from agencies to tell us when - it wrong. we rely on ground truth from agencies to tell us when we | from agencies to tell us when we mess. missed detections are misclassified.— mess. missed detections are misclassified. ., , , ., misclassified. the worry is that if the olice misclassified. the worry is that if the police often _ misclassified. the worry is that if the police often don't _ misclassified. the worry is that if the police often don't know- misclassified. the worry is that if the police often don't know for. misclassified. the worry is that if i the police often don't know for sure whether shot spotter got it right than they are not always reporting when the company gets it wrong. random accident public defender that specialises in forensics, he leaves