An in-depth look at stupidity and things that we do not know we don't know. The article by Errol Morris starts out with an interview of David Dunning, Cornell professor of social psychology.  David Dunning is one-half of the Dunning-Kruger team that wrote the paper, "Unskilled and Unaware of It: How Difficulties of Recognizing Ones Own Incompetence Lead to Inflated Self-assessments," was published in Journal of Personality and Social Psychology, Vol 77(6), Dec 1999, 1121-1134. doi: 10.1037/0022-3514.77.6.1121. Dunning and Kruger state in their paper:

When people are incompetent in the strategies they adopt to achieve success and satisfaction, they suffer a dual burden: Not only do they reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the ability to realize it.  Instead, . . . they are left with the erroneous impression they are doing just fine.

In other words, those who are incompetent are unable to recognize their own incompetence.

A YouTube video describing how to perform a self-check for testicular cancer. Each man needs to check his testicles periodically to feel if there is a change in the shape and contour of each testicle. It is not uncommon for one ball to be larger than the other. But, a firm lump (mass) in one of the testicles is not normal. If a man feels a lump that was not there before or a lump has gotten larger, then a doctor visit is a must.