Jonathan Gruber’s health-care forecasting is failing in Colorado as Vermont’s Gov. Peter Shumlin prepares to use the economist’s math for single-payer health care.

As Vermonters anxiously await a Gruber-modeled financing plan for Green Mountain Care, modeling done for Colorado’s health exchange by Jonathan Gruber Associates has proven wildly erroneous.

In 2011, following Colorado’s decision to set up a state health exchange for Obamacare, the state hired Gruber to forecast enrollment trends from which the state and federal government could estimate costs.

According to a presentation delivered to the Colorado Health Benefit Exchange Board on Sept. 16, 2011, Gruber predicted Medicaid enrollment in Colorado would grow from 440,000 enrollees in 2011 to 710,000 enrollees in 2016.

Actual 2014 data reported by the Colorado Department of Health Care Policy and Financing shows the number of people enrolled in the state’s Medicaid program has grown to more than 1.1 million — a miscalculation of about 400,000 enrollees.

The miscalculation is growing rapidly, as the state reported 12,533 new Medicaid sign-ups in the two-week period between Nov. 15 and Nov. 30.

“Medicaid and CHP+ enrollments over the last few weeks show that we are still finding and enrolling low-income Coloradans into coverage,” Susan Birch, executive director of the Colorado Department of Health Care Policy and Financing, said in a Dec. 2 news release.

The errors are significant for Vermont. Shumlin has denounced Gruber for video statements disparaging American voters and rejecting government transparency, but he has continued to defend Gruber’s math.

In November, Shumlin said Gruber would continue to serve as “a calculator” for single-payer financing options, despite not receiving additional pay. State health officials assert Gruber is one of only a few people in the nation capable of providing customized health-care forecasting data for states. Importantly, the Gruber Microsimulation Model used for Colorado also is being used to create financing scenarios for Green Mountain Care.

“His models can’t be relied on for policy. They’re not ready for prime time,” Linda Gorman, director of the Health Care Policy Center at the Independence Institute in Colorado, told Vermont Watchdog.

Read more at Watchdog.org