Hi George,
I recommend a change to the way that these statistics are obfuscated. The
problem is that new noise is used every day, and from the distribution of the
reported bins, the exact location within the bin (assuming the stat stats
constant) can be reported.
So instead of this
> +--------------+ +--------------------+
> actual value -> |additive noise| -> |round-up obfuscation| -> public
> statistic
> +--------------+ +——————————+
I recommend that you flip the order, so that it is like this
+--------------+ +--------------------+
actual value -> |round-up obfuscation| -> |additive noise| -> public statistic
+--------------+ +——————————+
“Additive noise” in the context of bins is actually just a distribution over
bins. You can think of it in two ways:
1. Add Laplace noise to the bin center, and then report the bin of the
resulting number.
2. Choose a bin using a two-sided geometric distribution centered at the
correct bin.
I believe that these are equivalent.
Best,
Aaron
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