Consider a situation in which two companies hold data about individuals: the first company holds individual's names, and their age.
The second company also holds the individual's name, but instead of holding their age they have their salary.
The state is interested in doing analysis of how age and salary are correlated: so would like to build a data base of the pairs (age, salary), however they wish to do so without being able to identify individuals, and without requiring the two companies to share their data.
Is there a data sharing strategy that the state and the two companies can devise so that:
- The state has the pairs (age, salary).
- None of the parties (state, or companies) can identify any given individual's age and salary.
A few points / thoughts:
I am working with the assumption that names are unique, so that if one party had both the (name, age) and (name, salary) data then they would be able to uniquely determine the (name, age, salary) data; but this strategy itself violates requirement 2.
Using just the name, age and salary variables it seems clear to me that this cannot be solved: if either company gives their names to the other this is of no use, likewise if they provide their age/salary data alone the other company cannot use it. And if both companies provide the age / salary data to the state then they alone cannot join the data.
So this leaves the question of whether additional anonymised identifiers can be created between the three parties to achieve the objective?
Update / Extension I realise that in wording the question I have over simplified the situation I am actually interested in, but the solutions below have been enough for me to adapt to this case.
In my scenario (and as one would expect in the real world!), the names held by the two companies do not match exactly.
This means that the succinct solution of @TwoBitOperation cannot be applied.
Further to the above, I will add the constraint that the two companies are only willing to share their data directly with the state (both names, and attributes).
I have posted my solution to this adaptation below (though refuse to accept my own answer, as it is heavily inspired from others' contributions).