Quote from saliva:
Has anyone actually done a research on the price correlation between the two CL contracts (ie. do they move in synch, etc)?
I did a very crude analysis on something related with daily data from the EIA website since 2000. I didn't look at the details on when they roll or a lot of other stuff because I am not trying to trade this, just control for calendar effects in the data while I look at something else. But here's what I found FWIW:
1) regressing daily spread changes (second - front contract prices) on monthly dummies, nothing is statistically significantly different from 0 and point estimates are pretty much +/- 1 penny.
2) looking at daily spread changes by day of the month, the only days that average outside +/- 5 cents are the 14, 16, 18, 20-23 and 31. They are pretty noisy.
3) regressing today's spread change on yesterday's, the spread changes are strongly mean reverting at the daily level across all days, but when you look one day at a time there are alot of days of the month that tend to move in the same direction as the last day.
4) regressing today's back contract price change on the today's front month price change, overall the r-squared is 88%. Most days it is in the 90's, it only drops much below that around the 20-23, with the lowest being 56% on the 22.
All of this is contaminated by not knowing the roll date EIA uses, it is not a continous contract. And if I were serious about it I would probably measure the days in days from expiration rather than day of the month.
I'd post an excel file but the website won't let me tonight.