"In the case of the taxi data, one way to improve on the hashing would be to substitute a random number for each license ID, then hash the random numbers. Not o

"In the case of the taxi data, one way to improve on the hashing would be to substitute a random number for each license ID, then hash the random numbers. Not only does this make the hashed values harder to re-identify (because the input has no consistent format), but even if the data are re-identified, the random values are not personally identifiable." What is the point of re-hashing the random numbers? Once you have replaced the actual values with random numbers I don't know what you get from then hashing those.