Are you calculating Monero to USD? If not then it'll be a flawed comparison.
Why? There is no such thing as a Monero/USD trading pair. It doesn't exist in nature.
OK I can do this for you too, but I can tell you now it won't matter, Monero is still more volatile than bitcoin. I'll have to do it tomorrow though, unless you want to do it first. Be my guest.
Feel free to correct me, but basing the Monero volatility off the btc/xmr price will simply cause Monero to constantly change based on the changing price of bitcoin. Even if Monero were stuck at $2 it'll look volatile because of Bitcoins swings.
Your calculation takes the bitcoin to Monero pair into account and I understand that there isn't a USD pair for comparison, although a USD price could be calculated, the trouble is many people may be buying and selling based on its USD value even if it has to be calculated by the trader.
I can't do any comparison myself right now because I'm on the train to work.
In just feel it's not a good analysis because bitcoin it's calculated pegged to USD and Monero is calculated pegged to Bitcoin, I think it'll be impossible for any coin pegged to a currency to be less volatile than that currency.