A motivated intruder test is a test in which an individual or group takes a data release and specified resources and attempts to re-identify one or more individuals in the de-identified dataset. Such tests specify the amount of inside knowledge, computational resources, financial resources, data, and skills that intruders possess to conduct the tests. A motivated intruder test can determine if the de-identification is insufficient. It can also be a useful diagnostic tool to assess if de-identification is likely to be sufficient. However, the test alone cannot prove that de-identification is sufficient.