Precision or Recall when dealing with critical cases?
Let us say your target variable &quot;1&quot; represents &quot;Harmful Object&quot;.
Precision answers the question - Of all objects predicted as Harmful - How many are really harmful ?
Recall answers the question - Of all the Harmful objects out there - How many were correctly identified ?
You want to increase on Recall in your case - since that reduces the overall risk to the machine.