Poor Sally. She has spent tens of thousands of dollars and four long years to get her college degree and has $26,000 in student loans to pay off, yet she can’t find a job that puts her degree to good use. Sally and her parents may be asking whether college was “worth it.”

Sally epitomizes many of her fellow college graduates who wonder why college graduates can’t find good jobs.

The experts give all sorts of explanations for Sally’s plight.

One of the most perplexing and frustrating explanations is that Sally is over-educated.

Think of the psychology major who brewed your Starbucks coffee this morning, or the Uber driver with the degree in philosophy who took you home last night.

Almost half of all recent college graduates are working at jobs that don’t require a bachelor’s degree, according to a study from the Federal Reserve Bank of New York.

While it might have been rare to see college graduates in these low-quality jobs a few years ago, they’re increasingly the norm these days. That same New York Fed study found that more and more recent college graduates are taking low-wage jobs and working part-time while fewer and fewer of them are working full-time at high-quality jobs.

Wharton School professor Peter Capelli tried to figure out whether the problem in the labor market is because the jobs don’t require the skills that candidates are offering or because workers don’t have the proper skills that employers are seeking.

Here’s what he found. The main problem with the U.S. job market isn’t a gap in basic skills or a shortage of employees with particular skills, but a mismatch between the supply and the demand for certain skills. There’s a greater supply of college graduates than a demand for college graduates in the labor market.

This mismatch, according to Capelli, exists because most jobs in today’s economy don’t require a college degree.

“Indeed, a reasonable conclusion is that over-education remains the persistent and even growing situation of the U.S. labor force with respect to skills,” Capelli said in his study.

Given all the non-economic benefits to a college education, it’s hard to call having too much education a “problem,” but in light of Capelli’s findings, it’s worth noting that women are the ones who are getting educated.

Women now earn about 60 percent of the roughly 1 million bachelor’s degrees granted each year, about 80 percent of women age 25 to 29 have a college degree, and about 30 percent of all women above age 25 have a college degree or more.

Those degrees, however, aren’t translating into good jobs.

Which means that maybe Sally’s problem isn’t because she’s not qualified for the job, but, instead, is because Sally has skills that employers don’t want.

Maybe the U.S. economy isn’t generating the types of jobs that require a college degree.

A look projected job growth shows that good jobs will be hard to find. At a median wage of $83,580 a year, the occupation with the fastest projected job growth, industrial-organizational psychologists, pays well. But, there’s not much demand for this type of psychologist. The field will generate only 900 jobs in 10 years, according to the Department of Labor’s Occupational Outlook.

The next fastest growing occupation, personal care aides, will generate a lot more jobs — more than 58,000 a year compared with 90 a year for the specialized psychologists — in that same time period. That occupation, however, isn’t very appealing to Sally with her bachelor’s degree. A personal care aide doesn’t need a high school degree, much less a college degree. And the job pays commensurately for this level of education: $19,910 a year.

More generally, the occupations with the fastest growth — personal care and home health aides and skincare specialists — tend to pay low wages. And, as the National Women’s Law Center’s report underpaid and overloaded: women in low-wage jobs noted, women make up a disproportionate share of the fast-growing, low-wage workforce.

This job growth is sort of good news for women. The jobs don’t pay well, but at least they exist.

In what should also be considered good news, highly educated women aren’t taking very many of these low-wage jobs. Women with at least a bachelor’s degree make up only 5.5 percent of the low-wage work force, according to the NWLC.

This leads to a second explanation for Sally’s plight: She may be undereducated.

Given the woes of the underemployed college graduate, it’s paradoxical that one reason that Sally may not be able to get a good job is because she doesn’t have enough education.

Yet, a close look at the educational requirements for the jobs with the fastest growth shows that many of these jobs aren’t open to mere college graduates.

Consider psychology, where women make up nearly 75 percent of degree holders. As indicated above, the field of industrial and organizational psychology is projected to be the fastest growing occupation over the decade. Not only is it fast growing, it’s also high paying. A typical IO psychologist will make $83,580 a year. However, getting a job as an industrial and organizational psychologist isn’t a piece of cake. There are very few new jobs opening each year and the job requires several years of education beyond the bachelor’s degree. Depending on the specialty, psychologists must be licensed, obtain a doctorate in psychology, complete a multi-year internship, and pass a professional exam before they can practice psychology.

In fact, if they don’t have an advanced degree, graduates with a bachelor’s degree in psychology will likely be working as a human resources assistant, mental health technician or sales associate.

That may be the reason why a recent survey by Payscale showed that almost half of all graduates with a degree in psychology were underemployed. The reason they feel underemployed is because with a median salary of $38,200 they feel they are underpaid.

This analysis leads to a final reason why Sally can’t get a good job with her college degree.

She has the wrong degree.

Students with traditional liberal arts degrees frequently find themselves underemployed, while students with degrees in science, technology, engineering and mathematics have little trouble finding good jobs in their profession. Nine out of the top 10 least underemployed majors are in STEM (law is the exception).

Women, however, aren’t studying STEM. Biology is the only STEM degree among the top 10 most popular bachelor’s degrees for women, and it comes in slightly above English language and literature as a preferred degree. Moreover, women aren’t making up for this gap by studying science and technology in graduate school — not a single STEM subject makes it among the top 10 master’s degrees for women.

Putting these three explanations together — too much education, not the right level of education, the wrong degree — paints a worrisome picture for the job prospects of college-educated women.

On the one hand, a college degree provides a needed credential to get a job, even if that job doesn’t require a college degree. But, on the other hand, if a woman wishes to move up on the pay scale, she may have to consider dropping her liberal arts degree in favor of a more technically-oriented degree, like engineering or physics. Barring these changes, women may find that they are very well-educated, but not necessarily very well compensated.