AUGUSTA — A labor researcher said Monday that Maine business organizations used faulty math and misinterpreted his work to support a more modest counterproposal to the $12-an-hour minimum-wage ballot question likely headed to voters this November.

But a spokesman for the Maine State Chamber of Commerce defended his coalition’s $10-an-hour proposal, which he said is supported by the business community and is less likely to impose a burden on employers.

The conflicting narratives came days before the Legislature will decide whether Maine voters will see one or two proposals this fall to increase Maine’s minimum wage.

The progressive Maine People’s Alliance and labor unions collected enough petition signatures for a ballot question asking voters to increase Maine’s minimum wage from $7.50 to $12 an hour by 2020. Business groups, however, are hoping to use the “competing measure” option available under the Maine Constitution to propose a wage hike to $10 an hour in 2020, which would appear alongside the $12-an-hour ballot question.

The Maine People’s Alliance once again sought to undercut the competing measure Monday by questioning the math behind the $10-an-hour wage.

Professor Michael Reich of the University of California at Berkeley’s Institute for Research on Labor and Employment suggested that the two business groups were misinterpreting the institute’s work in order to justify their more modest wage increase.

“It seems to me their arguments for a $10-an-hour minimum wage by 2020 are actually more appropriate … for the $12 minimum wage,” Reich said during a conference call with reporters Monday.

On several occasions, including in a March 2 press release, the business coalition cited the research institute’s studies in claiming that “if minimum wages are raised to no more than 60 percent of median wages, the net economic benefit is largely positive to both workers and business owners.” The business groups argued that their $10-an-hour proposal is more likely to have a positive benefit on workers and employers than the $12-an-hour proposal.

But in a letter dated last Friday and during a telephone call Monday, Reich said the business groups were using the wrong dataset. Instead of using the projected median wages for all workers in 2020 – including part-time and seasonal workers – the business coalition should have made its computations based on the median hourly pay for full-time workers, Reich said.

The projected median wage in Maine for full-time hourly workers in 2020 is $21.23. The $12-an-hour minimum wage would equal 57 percent of that median wage, just shy of the 60 percent cited by the institute.

By comparison, the business coalition is using $16.29 as the projected median wage for 2020. That puts the $10-an-hour minimum wage proposal just below the 60 percent tipping point cited by Reich.

“I request that you issue public corrections regarding both your arithmetic error and your misinterpretation of the minimum wage scholarship of the Institute for Research on Labor and Employment,” Reich wrote to the groups on March 11.

Representatives for the Maine State Chamber of Commerce and the Maine Restaurant Association said they would review the institute’s work and their characterization of it in their media materials.

But Peter Gore, vice president of the Maine State Chamber, accused the Maine People’s Alliance of “cherry-picking” numbers in order to arrive at a higher median wage. By only including full-time workers in that calculation, Gore said, they are excluding Maine’s many part-time workers. Gore noted that one of those workers, a woman who works three part-time jobs, spoke during the Maine People’s Alliance news conference.

“They don’t want to include her wages in the calculation of the median wage. That’s just cherry-picking the numbers,” Gore said. “We think we have a more honest and complete picture of what the median wage ought to look like.”

Gore also pointed to a survey of roughly 200 Skowhegan-area businesses by the local chamber of commerce as proof that businesses were on board with their proposal. Roughly 75 percent of the businesses that responded said they would support the business coalition’s proposal over the $12-an-hour plan. Additionally, 59 percent of the business owners said they would be less likely to hire new employees at $12 an hour, and more than 40 percent indicated they might have to shed workers.

Mainers should expect to see a slew of political and parliamentary maneuvering in the coming days on the minimum wage issue.

Lawmakers are expected to send the $12-an-hour proposal directly to voters rather than approve it themselves. Republican legislators plan to try to introduce the business coalition’s $10-an-hour “competing measure,” but are likely to face opposition in the Democrat-controlled House.