What does 3,410 vacancies mean?

The teacher retention and recruitment crisis keeps getting worse.

Since I was your age, I knew I wanted to teach. For my entire adult life, teaching has been more than my job: it’s been my identity, my passion, my commitment to my community. It is hard to walk away from that, especially as I still believe that education–a free, quality, public education–is a public good that can transform our society and the lives in it.

-Samantha Rainwater, “A letter to my students on my last day of teaching”

If I want to demonstrate that Derek Jeter is a great baseball player, I can sit you down and describe every at bat in every Major League game that he’s played. That would be raw data, and it would take a while to digest, given that Jeter has played seventeen seasons with the New York Yankees and taken 9,868 at bats.

Or I can just tell you that at the end of the 2011 season Derek Jeter had a career batting average of .313. That is a descriptive statistic, or a “summary statistic”.

The batting average is a gross simplification of Jeter’s seventeen seasons. It is ea…