| 摘要 |
An appropriate index value for guaranteeing the anonymity of data is specified, even when the number of items of data included in a predetermined group increases or decreases with time. An anonymization index determination device: specifies, with regards to data having an attribute, the number of items of data having each attribute at each point in time within a predetermined period; calculates for each threshold value the number of times the number of items of data having one attribute is equal to or greater than a given threshold value at a first point in time and less than the threshold at a second point in time; calculates a score for each threshold value on the basis of the calculated number of times; specifies an anonymization index, which is a threshold value specified on the basis of the score; and specifies an item of data having the one attribute and the aforementioned other attributes as an item of data to be updated to shared attributes when the number of items of data having a given attribute is less than the anonymization index and the sum of the noted number of items of data and the number of items of data having one or more other attributes is equal to or greater than the anonymization index. |
