Last spring I asked EconLog readers about the obviousness of on-the-job incompetence.  Most people thought incompetence was very obvious indeed.  It turns out that this view is widespread.  The General Social Survey asks:

In your job how easy is it for you to see whether your co-workers are
working well or poorly? On a scale of 0 to 10 please describe with 0
meaning not at all easy to see and 10 meaning very easy to see.

The distribution of responses:


Doesn’t this confirm the practical irrelevance of the signaling model of education?  No.  The question asks about the obviousness of observed job performance of current workers, not predicted job performance of job applicants.  And as my whole series on firing aversion revealed, many employers retain incompetent workers despite the cost.  Credentials alone often put a job in your hands – and subsequent poor performance often fails to tear that job from your grasp.