If you live in Jackson, Miss., Obamacare is giving you a raw deal. A 27-year-old in Jackson pays $336 a month for the second-cheapest silver health plan on Mississippi's s federally run insurance marketplace. That is more than twice as much as the $154 a 27-year-old in Nashville would pay for the same type of policy, and the $138 for a similar person in Tucson. Across all 34 insurance marketplaces run by the federal government, the average is $287, about 25 percent cheaper. The reason for the higher prices in some markets? Paltry competition, say Leemore Dafny and Christopher Ody from Northwestern University, and Jonathan Gruber of the Massachusetts Institute of Technology. Jackson has only two insurers on the marketplace: Humana and Centene.