An escaped mutant is a finding; a killed one is noise

The score is a summary and the value is in the list of mutants that survived, each of which is a change to the code that no test noticed.

--- Original
+++ New
@@ @@
     public function isEligible(int $total): bool
     {
-        return $total >= 5000;
+        return $total > 5000;
     }

escaped. no test covers the boundary. and the boundary
is exactly where the business rule lives.

Boundary mutants are the most valuable finding by a wide margin — changing >= to > escaping means nothing tests the exact threshold, which is where every off-by-one bug in a pricing rule comes from. Reading the escaped list once teaches more about the suite than the score ever will. Chasing the number rather than the findings produces tests written to kill mutants, which is a worse suite.