I found the article:

http://www.bloomberg.com/news/2012-11-19/government-equals-g......

Government Equals Growth as Massachusetts Tops Ranking

Massachusetts ranked first in economic opportunity in a new index that bolsters President Barack Obama’s argument that government and education are essential for creating the conditions for growth.
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Told ya.

It doesn't look like they give any details about the calculation. They just give a chart that says this at the bottom:

"Economic Opportunity is determined by using a constructed variable which includes: unemployment rate, median household income, and income mobility."

http://www.thestatesproject.org/economic-opportunity/

It seems like you get penalized for living in a state with a low cost of living. I live in NJ, which has a high median income, but it is expensive as hell to live here. My rent more than doubled when I moved to NJ from Raleigh, NC.

Also, I guess "economic opportunity" doesn't include an attractive business climate. For example, from the Bloomberg article:

"Yet Massachusetts ranked 22nd on the Washington-based Tax Foundation’s state business tax climate index. Wyoming, with no corporate or individual income taxes, placed first and New York, last, according to Richard Morrison, a foundation spokesman."