Just a small point about comparisons. I agree that you can tell just by looking at the plot that they are extremely close to each other and quite frankly, I think that you could just leave it at that; it's close enough for non-professional stuff.

Since you seemed to want to crank out some analysis though, I'd say it's helpful to compare the averages over certain intervals as you have done but overall it's better to compare the

*difference* between the two on a point-by-point basis, i.e., subtract CT from PT for every point. You can then plot the difference on the same time scale as the absolute powers (though on a different axis so that you can actually see the small values). This would show any systematic errors that might exist at certain power ranges or that might develop after a certain period of time. You could then also look at the average difference over the intervals, similar to what you have done already. As a partial aside, the average of a difference is not same thing as the difference between two averages. So the average of the point-by-point difference may not come out to be the same as the difference of the averages you have already calculated.

More than you wanted to know...