When you pick a winner for a quiz giveaway we include all qualified subscribers in the pool of entries for a random winner to be selected from.
We then use the Mersenne Twister, which is a random number generator (to be specific, a deterministic random bit generator), to select a winner. It is called the Mersenne Twister because its period length is chosen to be a Mersenne prime.
How the Mersenne Twister works
Why do we use the Mersenne Twister method?
This method passes numerous tests for statistical randomness, including the Diehard tests and most of the TestU01 tests.
This method has an extremely long period of 2^19937 − 1. While a long period is not a guarantee of quality in a random number generator, short periods, such as the 2^32 common in many older software packages, can be problematic.
It is k-distributed to 32-bit accuracy for every 1 ≤ k ≤ 623.
This method generally creates random numbers faster than true random methods. A study found that the Mersenne Twister creates 64-bit floating-point random numbers approximately twenty times faster than the hardware-implemented, processor-based RDRAND instruction set.
This method is permissively licensed and patent-free, which allows us to use it for POPSMASH at no charge.
The result is that you can be confident that any social quiz giveaway in which the winner is selected randomly by POPSMASH was chosen securely and randomly.