Excel 2007 : Measure rate of change of non linear data sets

[maw230]

I have two sets of data on my line graph. Both have positive slopes. Neither are a perfectly straight line. Can I use slope to compare the rate of change between the two lines?

For example, Slope 1 = .74 and Slope 2 = .85. So, Line 2 will have a higher rate of change.
Is only using slope sufficient for comparing non-linear data sets?

[shg]

Reckon it depends on what the data means and what question you're trying to answer.