GenePING health care provider filtered view. A doctor viewing a patient's records. Note how only one document shows up, and no information is available as to whether that document is filtered or not. Comparison with the patient's view reveals that it is indeed a filtered document, but a doctor would not learn this from his view on the data.
Adida and Kohane BMC Genomics 2006 7:93 doi:10.1186/1471-2164-7-93