Empirical analysis of blockchain branches: once every 380 blocks? I've completed an empirical analysis of blockchain forks from block #300000 thru #400000. I found the following: (a) blockchain forks of length 1: observed every 380 blocks on average; (b) blockchain forks of length 2: none observed.

I recognize there is variation inherent in any such analysis, as different full nodes may produce different results.

Does the above data "ring true"? I am keen to hear from anyone with good data (or even good intuition) and especially eager to hear from anyone with different numbers.
Blockchain forks are an artifact from the network propagation and appear at random intervals (and far more often than what you observed). It is important to note that since nodes do not forward information that contradicts their view of the network, i.e., they have accepted one of the forks, you will not be able to observe all forks in the network, but only those that are propagated to you through the network.

For details on what causes blockchain forks and their impact on the security/performance of the network see Information Propagation in the Bitcoin Network (disclaimer: I am one of the authors).