It’s a frequent refrain among advocates and opponents of a $15 minimum wage: Just look at the studies.

As St. Paul officials consider whether to increase the citywide minimum wage and how quickly, interested observers on all sides of the debate are pointing to the experience of other cities as evidence of positive or negative outcomes.

One problem with looking at studies of a $15 minimum wage: None exist.

Sure, there’s plenty of conjecture based on preliminary data, including rival studies that have come to largely contradictory conclusions on the Seattle experience to date.

But no city other than San Francisco, which reached $15 on July 1, has rolled out a $15 minimum wage, at least not in full — not even Seattle, which inspired “Fight for $15” efforts coast to coast when it passed new wage laws in June 2014. Citywide, employers there won’t be required to pay $15 per hour until the year 2021.

In Minneapolis, where the first of seven annual wage hikes took effect this year, small employers won’t be forced to pay $15 per hour or more until 2024.

“It remains to be seen in Minneapolis what the impacts will be as we get closer and closer to the $15 figure,” said Courtney Blanchard, an attorney with Nilan Johnson Lewis who is working closely with Minneapolis employers on compliance. “The job market is a challenge, so to some extent, employers in some industries may already be raising wages to attract talent. I think we haven’t seen the effects yet.”

‘NO EMPIRICAL ANALYSES … POSSIBLE’

Many academic studies have looked at the impact of more modest federal and state wage increases in previous years and found little cause for alarm — increasing a statewide wage by 75 cents or so after years of wage stagnation generally isn’t that big a deal in terms of job impacts.

However, a November 2015 report from the National Employment Law Project sums up the challenge of predicting the net effect of the wave of recent, more aggressive wage laws that have yet to be fully implemented.

“The bulk of rigorous research on the minimum wage over the past two decades shows that the federal, state, and local wage increases that have been examined have had little adverse effect on employment levels,” the report states.

“Newly passed $15 laws in cities like Seattle, San Francisco, and Los Angeles, however, raise wages more than (the) previous policies analyzed. … And because these laws have not been fully phased in, no empirical analyses have yet been possible.”

Nevertheless, academics have attempted to get a better sense of how the gradual increases toward a $15 wage have affected workers, businesses and even food prices.

Will the experience of Seattle — a growing city with a strong tech center and a population of more than 700,000 — match up closely with that of St. Paul, a city less than half its size? Some have their doubts, but a growing body of academic papers examines the trends to date.

Here’s a quick roundup of academic studies of the minimum wage:

WAGES HAVE NOT KEPT PACE

The Economic Policy Institute — a labor-affiliated Washington, D.C.-based think-tank that advocates for faster wage growth and higher labor standards — has pointed out how nationally, the buying power of the minimum wage has eroded with time. Workers at the lowest rung of the earning ladder take home less money than they once did, adjusting for inflation.

In fact, the purchasing power of the minimum wage peaked in 1968, at the rough equivalent of $10.85 in today’s dollars, according to economists. Some experts have said it would actually take $12 or more to keep pace with today’s cost of living.

The federal minimum wage — $7.25 — has not increased since July 2009. Minnesota’s minimum wage this year is $9.65 for large employers and $7.87 for small ones. The state defines small employers as businesses with annual gross revenues under $500,000.

Seattle’s $15 minimum has been phasing in gradually over almost seven years, with wage increases taking place each January. Wages reached $15 this year for large employers, and will hit $15 in 2019 for small employers that don’t offer medical benefits or tipping. All employers must pay at least $15 per hour in 2021.

And what’s the definition of “small employer”? That can vary broadly by municipality, but in Seattle, it means all companies with 500 or fewer employees. In other words, a sizable chunk of the city has yet to hit $15.

BAD NEWS OUT OF SEATTLE — AND GOOD NEWS, TOO

The impact to date out of Seattle is a bit cloudy — as in tough to interpret.

A University of Washington study, which focused on single-site employers (as opposed to chain stores), found the downsides of wage increases for low-wage workers in Seattle outweighed the benefits 3 to 1, costing the average worker $125 a month in lost work hours.

A competing study from the University of California, Berkeley, however, focused even more narrowly on the food industry, and found that rising wages had no major impacts on restaurant hiring. In fact, a food writer for the Seattle Times chronicled the opening of more than 40 restaurants in a six-week period last summer.

That’s good news or bad news, depending upon how you slice it.

Seattle raised wages from $9.47 to $11 per hour in 2015, and then to $13 in 2016.

The 63-page University of Washington report, published last year for the city of Seattle through the National Bureau of Economic Research, looked at the impact of the second increase and concluded that employers trimmed low-wage jobs by 6.8 percent or cut hours by about 9 percent. Related Articles Sept. 30 is last day for public comment on Pigs Eye Lake makeover

Staffers at MPR’s music stations The Current and Classical MPR vote to unionize

St. Paul woman sentenced for manslaughter in man’s death; murder charge dismissed

Ford Foundation grants $2.5 million to St. Paul’s Penumbra Theatre, a record for the Black arts organization

With new shops and street improvements, Saturday’s ‘Rice and LarpenTOUR’ showcases three cities

Hourly wages, which increased 3 percent, failed to offset those losses.

“Total payroll fell for such jobs, implying that the minimum wage ordinance lowered low-wage employees’ earnings by an average of $125 per month in 2016,” the report said.

Curiously enough, the first wage hike did not have such a dramatic impact, according to the University of Washington study: “Evidence attributes more modest effects to the first wage increase. We estimate an effect of zero when analyzing employment in the restaurant industry at all wage levels, comparable to many prior studies.”

For technical reasons, the University of Washington study excluded employers with multiple locations as it reviewed state payroll data. The researchers noted that single-site employers employ 62 percent of the workforce.

Critics say the study leaves out a cornerstone of industry: chain stores. Excluding chain restaurants and other multisite employers could skew the results, particularly if some fast-food and retail chains grew as smaller employers shrank. That’s according to a critique from the Economic Policy Institute, which took issue with that and other various aspects of the study’s methodology.

A separate study last year from the Center on Employment and Wage Dynamics at the University of California, Berkeley, focused exclusively on the Seattle food-services industry. It analyzed county- and city-level data from 2009 to 2016, and compared the data with that of other areas in Washington state and the rest of the U.S. to construct a parallel, or “synthetic control.”

Comparing the two groups, “our results show that wages in food services did increase — indicating the policy achieved its goal,” the researchers reported. “Wages increased much less among full-service restaurants, indicating that employers made use of the tip credit component of the law. Employment in food service, however, was not affected.”

Yet another study examining 137 wage increases across the nation found that while rising wages tended to eliminate jobs that paid below the new wage, the losses were offset by new jobs at or above the new minimum wage.

FOOD PRICES AND THE BENEFITS CLIFF

Hiring and work hours aren’t the only areas that could be affected by a higher minimum wage.

Food prices, employee benefits and job quality could see some affects, as well. There’s also been some discussion in academic circles of the “benefits cliff” — the point at which a worker who qualified for public assistance will no longer be eligible because they earn too much money.

Rising wages could gradually reduce access to public benefits for low-income workers, but the impact will vary widely depending upon each worker’s situation and the type of benefit, such as child care benefits, federal housing subsidies, home-heating aid and food assistance through the Supplemental Nutrition Assistance Program. There’s some fear that the net effect of rising wages could actually reduce household incomes or quality of life.

A study last year from PHI, which does national elder-care advocacy, found that a home health aide in New York City effectively took home more money earning $35,000 per year than $40,000 per year after public assistance was taken into account.

DON’T EXEMPT YOUTH WAGES?

Then there’s the question of youth wages.

Should teen workers make $15 an hour to start? Critics say that bakeries, ice cream stores and other employers of young workers will do the math and figure that it’s more cost-effective to hire an experienced adult worker full time than to piece together hours for teen employees who may need more training and supervision.

Related Articles Sept. 30 is last day for public comment on Pigs Eye Lake makeover

Staffers at MPR’s music stations The Current and Classical MPR vote to unionize

St. Paul woman sentenced for manslaughter in man’s death; murder charge dismissed

Ford Foundation grants $2.5 million to St. Paul’s Penumbra Theatre, a record for the Black arts organization

With new shops and street improvements, Saturday’s ‘Rice and LarpenTOUR’ showcases three cities On July 18, two researchers with the labor-affiliated National Employment Law Project called on St. Paul to follow the lead of Minneapolis and other cities about exempting youth workers from a $15 minimum wage: Don’t do it.

Their fact sheet, posted on the NELP website, points to studies that show minimum wage increases have had little negative effect on youth employment in the past. They noted that youth-training exemptions are often limited to 30 to 120 days, which could serve as extra incentive for fast-food and retail employers — industries where many businesses already have 100 percent turnover — to replace their workers as often as possible.

Those exemptions, they say, could also serve as a disincentive toward hiring older workers.