"Low Education Whites Dying Younger" May Be a Statistical Artifact, Not A Real Worsening

It has been widely reported that low-educated whites have had increased mortality at younger ages, reversing the decades-long trend of all groups living longer in the U.S.  Indeed, the "decline of the white working class" has been the main explanation of who the Trump voters are.

However, this Slate piece points to another possible explanation: the "low-education white" population has changed over time, with the healthier getting more education (and thus moving out of the "less than high school" category).

This takes us into the statistical weeds, and is not a sure thing.  What might have happened is this:

White people who did not finish high school have always been less healthy than more educated white people.  Nonetheless, for a long time, white people of all levels of education have been living longer.  Recently, though, "less than high school whites" started dying younger.  This could mean that this whole group is actually dying younger - they are less healthy, are smoking, drinking, and taking drugs  more (especially opioids), and are committing suicide more.

However, it could also be that the healthiest part of the group of low-education white people used to stop before high school graduation, but now they finish high school.  Even if the overall longevity of these people stayed the same, by using "less than high school" as the dividing line, it appears that the least educated are also dying younger.

As evidence, this article cites a paper which found that if we look at the lowest quartile of whites, there has been no decline in longevity.  It could be that, a generation ago, much of the lowest quartile of whites did not finish high school, so these two categories were very similar.  Now, with more people finishing high school, the "less than" group is smaller and composed of the worst off (who die sooner), while a rising portion of the lowest quartile are now high school graduates.