I do not understand why the values of certain variables changed from the previous version to the current version. For example, grad_debt_mdn for the first observation (unitid=100654) is 25106 in MERGED_2010-11 datafile in the current version (updated on Sept 13, 2016). However, grad_debt_mdn for the first observation (unitidi=100654) is 27070.5 in merged_2010_PP in the previous version (updated on March 2, 2016). Given that the variable grad_debt_mdn from Merged_2010-11 measures NSLDS AY2009-10, AY2010-11 pooled cohorts, why should the value for grad_debt_mdn change when the data was updated? I did the checking and it was not caused by the inflation adjustment. I noticed this change also happened to a lot of other variables such as FIRSTGEN_YR6_N.
I thought the only update was adding the most recent data file "MERGED_2014-15 datafile", but apparently it is not the case. So how was the data updated? Is there a document that can show me the things you did to update the data?