The invention concerns a data anonymity measuring device for selectively transmitting an anonymised database to a third party comprising: calculation means (402) coupled to at least one memory, the memory storing an original database (204) and said anonymized database (206), said calculation means arranged to calculate the conditional entropy for each entry in said anonymized database based on entries in said original database; comparing means (406) arranged to compare at least one of said conditional entropies with a threshold value; and output means (410) arranged to transmit said anonymized database based on the result of said comparison.