That form of formalized on-the-job training for specific jobs - like electrician, plumber, carpenter and steelworker - comes at a low-cost for the participant, and fuels the state's economic drivers that use construction trades.

The state already is looking at expanding its Skilled Trades Training Program beyond the $30 million it's already spent, while also considering ways to boost career tech education in Michigan's middle and high schools.

The reason: It's critical for Michigan's economic development to fill its nearly 100,000 open jobs and train for the retirements coming in the next 10 years.

"The prospects for people to get into the middle class is one of the big issues of our time," said Ken Sikkema, a partner in Public Sector Consultants, which released the study on Michigan apprenticeship programs.

He added: "The apprenticeships are pathways to good-paying jobs and a middle-class lifestyle."

According to the PSC study:

• Michigan averages about 2,000 apprentices per year since 2000.
• The top 5 programs represent about 2/3 of Michigan's apprenticeships: Electrician, construction craft laborer, carpenter, roofer and pipe fitter.
• The largest wage growth from beginning to end of apprenticeship programs, which can take up to six years, were for Electricians ($21.30 per hour at completion); pipe-fitter ($21.21) and carpenter ($19.73).
• About 80 percent of apprentices are affiliated with unions. And both women and non-whites are underrepresented: they make up 3 and 11 percent of all apprentices, respectively.

With enough skilled trades in the commercial construction industry, "nothing gets built," said Pat Devlin, secretary-treasurer of the Michigan Building Trades Council, one of the sponsors of the study. Other sponsors were Michigan's International Brotherhood of Electrical Workers and the National Electrical Contractors Association.