The Importance of Being Careful in Your Study About the Sources of Error

If you're not being careful in your study about the sources of error and therefore not being careful about things like counting visitors to a museum. This is why earlier on he said the less reliable your assistants are the less good they are at counting. So what David's driving home here is to point that if you're making errors then you can make these grandiose claims  that something about your findings in fact violate well-known laws of physics. And so we might wonder whether or not the result of a particular study which purports to violate some conventional law of physics is itself true.