I'm still skeptical about the 'hidden job market'

Very recently, I ran across another one of the repeated statistics that some majority of job openings are not actually posted. We've covered this before here (it's hard to believe it's almost been 10 years.) I'm rather fond of debunking these kinds of numbers, i.e. their baloney-ness stands out to me, and it is personally amazing to me that people choose to quote them.

I was really delighted to discover that I am not the only skeptic, and so today I point to Jesse Preston, a disability employment specialist who wrote up a very nice article on LinkedIn describing the origins of some of these numbers: 

The Ford Foundation-funded survey he is referring to is the pilot project conducted by the National Industrial Conference Board to gather labour market information from businesses which was done in Rochester NY. The results of which came out in the same year. 

We know this is the original survey of that statistic as this is the pilot project and literature from the "1965 Proceedings on Interstate Conference on Labour Statistics", which states that this survey is of great interest before launching a nationwide survey.  Up to this point, there has never been data collected directly from employers like this. 

In the report, they tested to see if job postings were a predictable metric for collecting labour market information. It was not. Their analysis shows that 25.1% of all the jobs hired by 27 companies surveyed appeared in the newspaper. Service jobs were the largest category within the 25.1% at 84.6% of the total service jobs hired were posted in the newspaper.

But if we consider that Mr. Haldane is only talking about career-type roles and not jobs in general, then we do not count the overall number of 25.1%. So, we must remove the service jobs and the unskilled labour roles.  Then you get 18.9% of jobs advertised in the newspaper. Therefore about 80% are not advertised in the Rochester Newspaper.

It is rather remarkable to me (and he is to be commended) that Mr. Preston actually tracked it down to a study from 1966 about the Rochester job market. I would have guessed it was manufactured out of whole cloth, but no, apparently not. 

Almost ten years later, I know that it's basically futile to either expurgate the internet (or people) of poorly sourced and dubious statistics or quantify the unquantifiable, but I am still very skeptical that we should refer to a "hidden" job market. I also am further skeptical that the 'hidden' market represents the majority of positions at any one time. 

I do find it reasonable that mid-career professionals are likelier to be able to access such "hidden" positions, i.e. if you have a unique skill set, it's likelier that organizations will make room for you in some fashion, but I think that talking about 'hidden job markets' for entry-level people is just more likely to give students and postdocs conspiratorial vibes more than anything else.