Table 1.

Example of data before (a) and after (b) categorizing date variables and adding a fuzzy factor (c)

IDDOB (day/month/year)Exam 1 dateExam 2 dateDiagnosis date
A. Entries in D1 realistic dataset
01071972 234561/7/19722/8/200010/11/200421/1/2007
31051970 6543231/5/19705/8/20051/12/200821/2/2011
03041960 456783/4/19605/1/199510/2/1998
20021981 8765420/2/198020/9/200610/8/200923/1/2010
B. Entries in D2 after categorizing date variables (applying k-anonymization, setting every date to the 15th)
00115/7/197215/8/200015/11/200415/1/2007
00215/5/197015/8/200515/12/200815/2/2011
00315/4/196015/1/199515/2/1998
00415/2/198015/9/200615/8/200915/1/2010
C. Entries in D3 anonymized and “fuzzified” (the fuzzy factors assigned in this case were +3 for ID001, −3 for ID002, +4 for ID003, and −1 for ID004)
102315/10/197215/11/200015/2/200515/4/2007
987515/2/197015/5/200515/9/200815/11/2010
456715/8/196015/5/199515/6/1998
234515/1/198015/8/200615/7/200915/12/2009