Whether older workers have medical insurance plays a big role in their decision to retire.

Researchers at Watson Wyatt Worldwide, Washington, a consulting firm, have come to that conclusion in an analysis of data collected from 1992 to 2004 by the University of Michigan Health and Retirement Study team.

The likelihood that workers ages 50 and over would retire in any given year was 16 percentage points higher for workers who had access to health care coverage from some source other than their current employers, the researchers report.

Having only a defined benefit pension plan, rather than some other type of plan or a combination of a defined benefit plan and another type of plan, increased the likelihood of retirement by 4.1 percentage points.

Home equity played less of a role in retirement decisions than anticipated Social Security or pension income played, the researchers report.