As I’ve written in The Best Posts About Attrition Rates At So-Called “Miracle” Schools:
Periodically, President Obama, Secretary of Education Duncan, or various newspapers will highlight so-called “miracle” schools (often charters) that have made quick and dramatic gains in test scores or graduation rates. The message is — since they can do it, why can’t the rest of us? Often, however, the student attrition rates behind those achievements are ignored. In other words, these schools often don’t make these gains with the same students, or they really don’t have a 100% graduation rate if you look at who they started with…
I was reminded of this when reading the Pickles comic strip today:
You can make the data look pretty good if you make sure the “water’s frozen over” before you report the numbers….