A new study shows that workers who had experienced help with their 401(k)s had higher returns. The study includes professionally managed funds, online resources and target date funds as sources of help. The returns averaged about 3% higher per year, which over a long period could add up to large differences at retirement. The study said that workers who pulled money out, or invested too heavily in one company made common mistakes, which those who sought help were less likely to make. The study found that about 30% of workers get help with their 401(k)s.