[phkahler]

>> It's the only way the reader will perceive the correct relative difference...

Every day, the stock market either goes from the bottom of the graph to the top, or from the top all the way to the bottom. Sometimes it takes a wild excursion covering the whole graph and then retreats a bit toward the middle. Every day. Because the media likes graphs that dramatize even a 0.1 percent change.

[KarlKemp]

No, the media just happens to sometimes share OP’s intend: to show a (small) absolute change. That change may or may not be as dramatic as the graph suggests in both visualizations: measured in Kelvin, your body temperature increasing by 8 K looks like a tiny bump when you anchor it at absolute zero. “You” being the generic “you”, because at 47 deg C body temperature, the other you is dead.

It will be visible if you work in Celsius, a unit that is essentially a cut-off Y axis to better fit the origin within the domains we use it for.

[wbsss4412]

The change still needs context.

We have an intuitive sense of what 30 degrees is, assuming it is in our preferred system of measurement.

A stock market graph really should be showing the percentage change, not some small absolute change that it’s not immediately understood by the typical layperson.