How to determine range for slope calculation

[Melpp]

I have data that has a baseline value then peaks and returns to baseline (somewhat). It does not contain valleys. I need to calculate the slope at which the value returns to baseline. I know how to calculate the slope in Excel VBA but how can I determine where the range ends (ie when it returns to a baseline value) when the baseline value fluctuates quite a bit.

 

[Ralajer]

Melpp, could you provide a representative sample set of the data with some additional comments. I get a feeling that I know what you mean but without specific data any answer would be a shot in the dark.