Do you see Millennials as digital natives, comfortable with technology, short on loyalty to their employers, devoted to their favorite causes, and enamored of Ping-Pong? If so, you're wrong. You may be doing them a disservice, and yourself as well, because you can't effectively manage people you don't understand.

That advice comes from Jessica Kriegel, author of Unfairly Labeled: How Your Workplace Can Benefit From Ditching Generational Stereotypes. She's a Millennial herself. As Kriegel points out, believing that Millennials are job-hoppers and that Baby Boomers can't work a  smartphone is not all that different from believing that Jewish people are good with money and women can't handle math. In other words, they're stereotypes that can blind you to the incredible variety of human beings you may encounter during your work life.

Besides, these stereotypes have no basis in fact. "Numerous studies show no significant differences between the three generations [Baby Boomers, Gen-Xers, and Millennials]," Kriegel says. So why do they persist? "An entire industry has been built around the concept of generational differences. So-called 'generation experts' have made a lucrative business out of selling snake oil to businesses hoping to understand the unknown."

Not only are these stereotypes inaccurate, they're liable to really annoy the people you're trying to understand. "I can't tell you how many times I have been told what I believe, what I think, what I value, and what I want," she says. "It is frustrating and it is unfair."

To help us all avoid falling into this trap, Kriegel has identified the two most common--and false--stereotypes about Millennials. Ask yourself if you've ever made either of the following assumptions:

1. Millennials are more comfortable with technology than everyone else. 

It seems logical enough: Millennials were born into a world where most people have smartphones, whereas Baby Boomers were born before even personal computers existed. But in fact, Kriegel says, research shows that employees of all generations have embraced the technological revolution.

This is why, she says, Whole Foods may be experiencing a backlash with its plans to open a Millennial-focused chain of stores. "The modern stores were less cluttered, incorporated technology, and they were less expensive. The implication in their marketing was that Baby Boomers did not want less cluttered, less expensive, modernized stores."

As for Kriegel herself--don't accuse her of being tech-savvy! "I have never had a Facebook account and I would be lost without IT's support."

2. Millennials are job-hoppers.

At first glance, this one might seem to be backed up by the research. For example, the Bureau of Labor Statistics reports that today's young employees hold an average 6.2 jobs between the ages of 18 and 26. While this may seem like a lot, Kriegel says, most Millennials hold a series of summer jobs and internships between the ages of 18 and 22, meaning they stay in their first "real" jobs for around three years.

Some of the other studies that show Millennials changing jobs frequently have been repeated over the decades and reveal the same high turnover rate for young people in the 80s and 90s--today's Baby Boomers and Gen-Xers. "It has more to do with life stage than with generation," Kriegel says.  

This is the kind of stereotype that can really hurt. "A Millennial once told me he was not being considered for a promotion because his boss believed he wouldn't be sticking around for long enough," Kriegel says. That sounds like a self-fulfilling prediction to me.