I was just thinking about statistics on traditional students vs. non-traditional, and realized that there are huge outflow issues in the way they are often presented.

[For more on inflows, stocks, and outflows, read this short description]

It’s common to talk about a decline in traditional students by saying things like “Only x% of students in 2012 were traditional, full time students.” But that’s a highly deceptive formulation.

Imagine a world where there are three students – two traditional full time students and one part time student who takes eight years to graduate.

Most reasonable assessments of this world will say that 2/3 of students are “traditional”. But at any given time it will look like only 50% of “current students” are traditional. Check it out:

Of course it can get screwy the other way too. Quick-finishing community college students would be undercounted in any year-to-year percentages. The point is that year-to-year figures are so horribly distorted by outflow issues that they need to be approached with extreme caution.