Right, limiting the survey to bowlers who played ODIs in 2004, the participants are: Harbhajan Singh, Glenn McGrath, Michael Kasprowicz, Ashley Giles, Muttiah Muralitharan, Dilhara Fernando, Chaminda Vaas, Nuwan Zoysa, Shaun Pollock, Jacob Oram, Jason Gillespie, Ian Bradshaw, Brad Williams, Heath Streak, Andrew Flintoff, Shoaib Malik, Daniel Vettori, Martin Suji,
Ray Price, Chris Harris, Shoaib Akhtar, Darren Gough, Brad Hogg, Shabbir Ahmed, Chris Gayle, Corey Collymore, Makhaya Ntini, Anil Kumble, Abdul Razzaq, Brett Lee, Mohammad Sami, Ajit Agarkar and James Anderson.
Their average List A economy rate is 4.28 and ODI, 4.35. We also tellingly get a Pearson Coefficient of 0.89 and R-squared value of 79%, which suggests that there's a strong correlation between the two, namely that 79% of the variance of the ODI stats is caused by the variance of the List A stats, which is easily significant (but I'd be concerned if good List A economy didn't mean good ODI economy).
However, I wasn't convinced that there was enough data to suggest that the stats "ODI" and "List A" were even significantly different. Reducing them to a T-distribution of 64 degrees of freedom with common variances (having conducted an F-Test to ascertain this case - look all this up if you want to understand the steps), I calculated a T-value of 0.81, which isn't large enough (needs to be 1.66) to prove, statistically that there's a significant difference.
So basically, we're all wrong.