From time to time we make revisions to the way that Prosper Ratings are calculated as part of prudent risk management of loans originated through Prosper.
For example, we may determine that a particular group of borrowers should be A-rated instead of B-rated. Once we make that decision, future applications from that date from those types of borrowers (or from other borrowers with comparable profiles) will be A-rated.
Note that current and closed listings are not affected by these changes. Those changes then raise the question of which Prosper Rating an older application might be assigned if it were to be evaluated freshly today.
To that end we create what we call “retroscores”. For example, Loan # 41515 was originally rated an A. Under the 4/28/2011 evaluation heuristic, however, it would have received an AA rating.
The file below contains retroscores for two of our more recent changes, dated April 28 and July 14 of this year. The file will be most useful for users of our Data Export and API tools, but all of our users are welcome to download and peruse it.
http://www.prosper.com/prm/data/ProsperRetroscoreDataFile-20110809.zip
NOTE: This file has more than 70,000 rows and therefore cannot be opened in Excel 2003. Additionally, be sure to load the LoanKey column as Text, as Excel 2007 will incorrectly convert some values to numbers upon opening.
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