When it comes to retirement plans, bigger isn’t always better.

A report released by Judy Diamond Associates, a Washington-based retirement and benefits plan analyst, breaks down retirement plans by plan size and industry showing that there’s little difference in outcomes between smaller plans and larger plans.

“As it turns out, a defined contribution plan’s success has nothing to do with the kinds of choices investors are being offered in terms of mutual funds,” says Eric Ryles, managing director of Judy Diamond Associates. “What seems to be the driver is how much the employer can convince employees to put into their retirement package. It’s all about participation.”

In the 401(k) Benchmarking Report, a study of approximately 480,000 401(k) plans, the 12-month rate of return for participants in small plans with fewer than 100 participants was 5 percent, little different from larger plans with their collective 6 percent rate of return.

Furthermore, plans serving profitable industry groups did not perform better than plans serving other sectors. Plans serving lawyers, finance and insurance professionals, and physicians fared no better on average in 2014 than plans serving construction workers, waste management workers and miners — all reported rates of return ranging between 5 and 7 percent.

“There’s nothing in our data to suggest that blue-collar professions receive advice, investment options or services that are of a lesser quality than white-collar professions,” Ryles says. “They may be getting less from their employers in terms of a matching contribution.”

Chad Parks, CEO of Ubiquity Retirement + Savings, a San Francisco-based company that provides IRA and 401(k) solutions to the small business space, says that plan performance is flattening out due to the widespread adoption of automation and passive investment products.

“In good times, a rising tide floats all boats, and in bad times it sinks them,” Parks says. “If people receive the advantage of compound growth just from participating in a savings plan, then the decision to auto-enroll employees as a company makes a significant difference for their future with little cost or effort.”

Average account balances formed a barbell distribution across plan size. The smallest plans, those with one to 10 participants or 11 to 25 participants, had the highest average account balances, at $76,000 and $57,000 respectively.

Other small-, mid- and large-sized plans, those between 26 and 5,000 participants, averaged account balances between $41,000 and $49,000.