The bias comes in where they only cite studies that agree with them (other studies are mentioned below). And then they say
"Despite evidence to the contrary, businesses and Republicans may keep pushing against the minimum wage — using the jobs crisis now to clinch their argument. They should be disregarded, because their argument is wrong and the United States is too rich to tolerate such an underclass."
See, all those other people are wrong! So disregard them! Don't pay any attention to them! That is clearly bias when you say only your opinion matters.
Now here is some other evidence:
"... research shows that in the long run the adverse effects of a higher minimum wage are quite substantial." (page 84, The Economics of Public Issues, 13e, by Roger LeRoy Miller, Daniel K. Benjamin, and Douglass C. North).
"In a new report, economists David Neumark of the University of California at Irvine and William Wascher of the Federal Reserve Board say a review of more than 90 studies in more than 15 countries since the early 1990s shows nearly two-thirds of the studies find a "consistent" though not always statistically significant negative impact on employment. Fewer than 10 found a consistently positive impact. While there's "no consensus," they say, "the weight of empirical evidence" supports the traditional view." (The Wall Street Journal, p. A4, Nov. 3, 2006)
From Greg Mankiw's blog: "Economists Richard Burkhauser (Cornell University) and Joseph Sabia (University of Georgia) report: a beneficiary from a proposed federal minimum wage hike to $7.25 an hour is far more likely to be in a family earning more than three times the poverty line than in a poor family. In total, only 12.7 percent of the benefits from a federal minimum wage increase to $7.25 an hour would go to poor families. In contrast, 63 percent of benefits would go to families earning more than twice the poverty line and 42 percent would go to families earning more than three times the poverty line."