Israel's 'anonymous' statistics surveys aren't so anonymous
In a workshop at Tel Aviv University, students discovered that much of the confidential personal information collected in social surveys by the Central Bureau of Statistics is publicly accessible.
It turns out that much of the confidential personal information collected in social surveys by the Central Bureau of Statistics is publicly accessible. Tel Aviv University students found a way to drill down into the statistical tables published by the bureau on its website to the level of individual responses and even glean the answer sets of specific survey participants.
In some cases the students were also able to identify the respondent despite assurances that the surveys are anonymous. It should be noted that anyone approached by the bureau to respond to its surveys is required by law to cooperate. Participants may be asked questions like: "How many times have you been married?", "Have you been sexually molested in the past 12 months?", and "What was your overall gross income last month?"
According to the university's Prof. Eran Tromer, the students made the discovery in a data security workshop at the university's school of computer sciences. The workshop was led by Tromer and Prof. Kobbi Nissim of Ben-Gurion University of the Negev, under the auspices of Check Point Software Technologies.
"We analyzed the 2011 survey," said Tromer. "Out of the 7,064 respondents we reconstructed 1,005 response records." Survey findings displayed on the statistics bureau's website allow viewers to break down the information in various ways.
"We showed that through sophisticated queries, the responses on questionnaires as given by the participants can be inferred and reconstructed to the point of obtaining a full profile," Tromer explained. "The person can sometimes also be identified based on their answer profile. Anyone possessing additional databases could cross-reference and easily identify respondents."
The bureau said in response that it is doing a thorough study of the report and its implications on methods used in the future. It also stated that it vigorously adheres to the Statistics Ordinance to prevent the exposure or identification of individuals in its surveys and will continue to do so.