This function is incredibly helpful for comparing dataseries. You can add it to your render URL like so;
Here's what that graph means.
- If both series are equal, then it will produce a graph that hovers around 0.
- If the second series is consistently lower, then the graph will be consistently > 0.
- If the first series is consistently lower, then the graph will be consistently < 0.
Here's a more in-depth explanation and use case.