The six year graduation rate data goes back to the kids who started college ELEVEN years ago. It is an extremely lagging metric. For purposes of the 2015 USNWR ranking, Katrina just happened this year.
The biggest factors in having a good 6 year grad rate are (i) having selective admissions (which Tulane has) and (ii) having a good freshman retention rate. That data lags much less. For this year’s USNWR formula, the freshman retention data is based on the classes that started in the Fall of 2009, 2010, 2011 and 2012. TU has a much improved 90% frosh retention rate for this group. For this metric, Katrina happened a few years ago and is fading away fast.
“A big piece of the formula (18%) is tied to six year graduation rate. This is what kills TU – 76%. By comparison, USC is 91%, NYU 84%, Miami 82%. This stat currently combines data for the freshmen classes that started in the Fall of 2004, 2005, 2006 and 2007. So very much a trailing/lagging metric. FYI, Katrina was Fall 2005. So it will be 2-4 more years until the lingering effects of Katrina are completely out of the data set.”