imagine if the number were -X billion. As I increase X, your estimate should respond. Surely there is an X such that you would notice, even though it is admitt

imagine if the number were -X billion. As I increase X, your estimate should respond. Surely there is an X such that you would notice, even though it is admitted the number varies, right? i.e. even a one-time -100000 billion month would be noticeable in your framework? From there we show that -100 is not quite as bad, and +100 is better. If a new employee is an hour late the first day on the job, it doesn't prove they're not committed but it sure points that way. Every observation is evidence, raising or lowering your estimates of reality behind the observations.