In a 2012 NYT piece we read that
The average age of a highly skilled factory worker in the U.S. is now 56. “That’s average,” says Hal Sirkin, the lead author of the study. “That means there’s a lot who are in their 60s. They’re going to retire soon.” And there are not enough trainees in the pipeline, he said, to replace them.
Is this analysis robust or is highly dependant on how one defines "highly skilled"? Has it been subject to peer commentary, etc.?