What are "informed personal essays?"

The question came up in class about personal essays: What are they?

For the purposes of this class, I always describe them as "informed personal essays," which results in blank stares and confusion. Probably the best way I can explain what I think makes a good personal essay and what I mean by "informed" is to gives some examples.

Let's start with a story from Tyrone Beason, who writes for The Seattle Times' Pacific NW magazine:

The story is mostly an account of his experience learning to swim. But there is other reporting as well:
    -- Quotes from reading he has done about swimming;
    -- Statistics on the racial/ethnic breakdown of who knows how to swim;
    -- Information on local swimming lessions;
    -- An interview with an Olympic gold medal swimmer;
    -- Interviews with other swimmers.

The result is a full package: His experience set in context.

Here's another one from The Seattle Times. In it, food writer Matthew Amster-Burton writes about his knife-sharpening skills, or lack thereof. But he also interviews a sushi chef and writes about improving his skills with an instructor.

Last one. This from the New York Times. In this piece, Patricia Morrisroe writes about how Emma, the voice of a rental car's GPS system, affects the relationship with her husband of 22 years, her obsession with "Wuthering Heights" and her journey in England in search of a moor romantic enough to fit her image of these geological formations. It's part travel story, part reminiscience, part humor and all very entertaining. There is less "informed" and more "personal" in this essay, but there is still information on places she visited and an obvious knowledge of the Bronte masterpiece.