State laws requiring consumers to buy medical insurance may be as ineffective as state laws requiring motorists to buy auto insurance.

Analysts at the National Center for Policy Analysis, Dallas, a group that is skeptical of government intervention in the marketplace, write in a paper on the issue that most U.S. states require drivers to own automobile insurance, while Massachusetts is the only state that requires residents to own health coverage.

The percentage of U.S. residents without health coverage is about 16%. Roughly 13% of U.S. drivers lack auto coverage.

The fact that the figures are so close suggests that state mandates may not have much effect on drivers’ decision to buy auto insurance, the NCPA analysts write.

The researchers found that the poverty rate and the cost of health care have a large effect on ownership of both health insurance and auto insurance.

A 10% increase in the poverty rate in a state correlates with a 7.4% increase in the uninsured rate for auto and a 7.1% increase in the uninsured rate for health in that state, the analysts estimate.

A 10% increase in the cost of health care correlates with an 11% decline in the uninsured rate for auto and an 8.5% decline for health insurance, the analysts say.