I remember reading in some older threads where board members had identified a specific series of bar code #'s, which reflected tighter graded books during that period. I found it very interesting and even wrote down one such series that had been discussed: barcodes starting with 093 to 097 as very tightly graded. I'm sure other boardies have information such as this, and of course it is subjective, but I find it quite enlightening to hear from others about their thoughts and observations on tighter and looser grading periods (or barcode series #'s which are identified as such)