In the world of defined contribution pensions, a plan’s investment menu is important because members’ choices are constrained by the funds that are available. And, while some may think it’s sufficient to use a third-party advisor for a DC plan, new research out of the University of Missouri suggested otherwise.

The new paper, which will be published in the Journal of Financial Counseling and Planning, examined retirement plan performance by studying advisor use, plan size and investment choice, comparing the performance of DC plans and their funds with and without third-party advisors against various benchmarks for the years 2013 through 2015.

“We selected defined contribution plans that had more than 100 participants because only those plans are required to report what funds are included in their plans,” says Rui Yao, the paper’s co-author and a professor and director of graduate studies in the personal financial planning department at the University of Missouri.

Once the research identified the plans, it divided them between those that use a third-party plan advisor and those that do not. It then selected Morningstar Inc. independent benchmarks to measure the performance of the plans in terms of return, risk and risk-adjusted returns.

The research found that in 2013, the best year in terms of market returns, working with an advisor was significantly and negatively related to retirement plan performance. In 2014 and 2015, it found only slight improvements or no significant results.

The results were surprising, says Yao, since at least two-thirds of plans used a third-party advisor, but it didn’t seem to help.

To address this, the paper suggested plan sponsors require advisors to periodically, and objectively, evaluate the performance of their plans.

The main takeaway for employers is recognizing that even when hiring advisors, they still bear the fiduciary liability, Yao says. “You have to evaluate the advisor’s job by looking at their performance because eventually the employers bear the fiduciary liability to the plan participants.”