I have edited the data so that site (nominal, S) can be used for both spine breaks (continuous, B) and logger data (continuous, L).

So now my question is, can I compare slopes of these comparisons (S v B and S v L) if they don't have the same number of data points?

For example, for site 1, there may be 75 'B' points, but 89 L points.

Also, I've heard something about using ANCOVA for this, but I also heard something about dummy columns..I'm not sure how to run this (I have 10 sites)

Any help would be greatly appreciated.