user540: I'm wondering if anyone has collected statistics on how often reorganizations of side-chains with length 1 happen in comparison with lengths of 2, 3, or more.
Related: What is the longest chain reorganization that has ever happened?

user19476: Random reorganizations of length more than 1 are rare. To get a fork of length 1, you need two miners find a winning nonce at nearly the same time. To get a fork of length 2, you need the same (1) happen right after a fork of length 1 and (2) have those miners mine on different sides of the fork.
However, such fork happen once in a while. See this answer for some statistics. And even longer forks happen due to bugs in Bitcoin code, like this one in March 2013.

540: <p>I'm wondering if anyone has collected statistics on how often reorganizations of side-chains with length 1 happen in comparison with lengths of 2, 3, or more.</p>

<p>Related: What is the longest chain reorganization that has ever happened?</p>
 19476: <p>Random reorganizations of length more than 1 are rare. To get a fork of length 1, you need two miners find a winning nonce at nearly the same time. To get a fork of length 2, you need the same (1) happen right after a fork of length 1 and (2) have those miners mine on different sides of the fork.</p>

<p>However, such fork happen once in a while. See <a href="/a/4638">this answer</a> for some statistics. And even longer forks happen due to bugs in Bitcoin code, like <a href="http://bitcoinmagazine.com/3668/bitcoin-network-shaken-by-blockchain-fork/" rel="noreferrer">this one</a> in March 2013.</p>
