Despite the sob stories you hear about unemployed college graduates, bachelor’s degrees have actually gotten more valuable over time. The wage gap between the typical college graduate and those who have completed no more than high school has been growing for the last few decades. In the late 1970s, the median wage was 40 percent higher for college graduates than for people with more than a high school degree; now the wage premium is about 80 percent.

Some of that wage premium has to do with the changing nature of American jobs and the skills (and social networks) attained in college. Some of it may have to do with a change in the mix of students who go to college and those who don’t. As college enrollment becomes more expected of high school students — as of October 2011, 68.3 percent of 2011 high school graduates were enrolled in college — the shrinking group of students forgoing college may have other characteristics that are associated with lower wages.

At the very least it seems as if more employers are using bachelor’s degrees as a signal of drive or talent, regardless of of the relevance of the skills actually learned in college.

That is one implication of an analysis from Burning Glass, a company that analyzes job ads from over 20,000 online sources ranging from major job boards to small and midsize employer sites. The company’s chief executive, Matthew Sigelman, says that employers are increasingly requiring college degrees for positions that did not traditionally require higher education.

I asked his company to compile a list of occupations that have shown the most “up-credentialing” in the last five years — that is, occupations whose job ads were significantly more likely to name college diplomas as a prerequisite in 2012 than they were in 2007.

Here is a look at the 10 occupations with the biggest percentage increases in requiring a college degree.

Occupation title 2007-12* Growth in % of Posted Jobs Advertising for a Bachelor’s Degree 2007 % of Ads Requiring Bachelor’s Degree 2012* % of Ads Requiring Bachelor’s Degree Dental Laboratory Technicians 175% 12% 33% Chemical Equipment Operators and Tenders 83% 6% 11% Medical Equipment Preparers 55% 11% 17% Buyers and Purchasing Agents, Farm Products 43% 54% 77% Electronics Engineering Technicians 38% 21% 29% Dental Hygienists 38% 40% 55% Architectural Drafters 37% 41% 56% Cargo and Freight Agents 36% 33% 45% Photographers 36% 25% 34% Claims Adjusters, Examiners and Investigators 35% 48% 65%

Some of these occupations may actually require more advanced skill sets than they used to. Others may require the same old duties and skills, but employers assume that people who don’t go to college in this day and age must be inferior candidates. There’s also still an oversupply of workers, so employers know they can afford to be picky.

A lot of jobs on this list fall into various categories of logistics. The people at Burning Glass say that college-level technical training, and not just possession of a fancy sheepskin, may be newly important in a lot of these positions.

“Supply chain management has gotten more complex, and companies have started to bring in quantitative expertise into roles like ‘purchasing manager’ that formerly would have been filled face-to-face by someone on the floor,” Mr. Sigelman said.

Many administrative jobs — human resources manager, property manager, school administrator, desktop publisher, security manager — also appear on the full list.

These tend to be jobs that require fewer technical skills, so it’s not clear why a college-level education would suddenly become more important — except maybe as a sorting device for narrowing down the deluge of résumés to the most qualified (or overqualified) applicants.

In most of these administrative occupations, hiring has fallen over the last few years, as you can see in the columns further to the right showing the total number of jobs posted. That could also mean that the openings that are left — the ones that have been harder to fill even when workers are abundant — are disproportionately the ones actually do require more advanced skill sets.

For other categories of jobs, it’s harder to tell whether the “up-credentialing” reflects changing job duties or mere degree inflation.

A lot of the jobs listed are medical technician positions, for example, which typically require some kind of technical skills that can be achieved with postsecondary schooling like an associate’s degree or a certification of some kind. It’s unclear whether these jobs have gotten more technically sophisticated in the last five years, or whether employers just want to narrow down the pool of potential applicants to those perceived to be more ambitious.