[barrkel]

That's just it: if the changes are only visible if you chop off the bottom of the graph, the probability they aren't significant increases.

[kolpa]

How would you feel if your body temperature increased 3%? Barely visible in a 0-based graph.

[barrkel]

What is a 3% change in body temperature? From absolute zero?

(My point is that temperature is probably an odd man out in graph terms, our usual reference points are not actually at zero.)