possibility for: same firstname, surename and birthday

[smadamit]

One task for anyone: estimate the possibility that two jugglers on a EJC have the same: firstname, surename and birthday

[smadamit]

see: https://github.com/inbaz/ers/issues/13#issuecomment-77804938

[smadamit]

@inbaz What do you think about a warning in the admin panel for that cases?

[smadamit]

I have an estimation. I was curious about this question.

assumptions:

• frequency for very common surnames: lower than 2%
• frequency for very common firstnames: lower than 5%
• age range at a EJC is much higher than 10 years

P(2 persons) = 0.02 * 0.05 * [ 1 / ( 10 * 365 ) ] = 1 over 3,650,000 P(EJC 8000 participants) = 1 over 456

Some assumptions are very conservative, so the real possibility should be lower. And I know that's only an estimation, since there may be dependencies between the probabilities. And in the end it is even less possible since one of the two jugglers with same name and birthday have to forget their eticket. Otherwise we have the matching number of the order and there is no confusion.

The following study for blood donations comes to the conclusion that firstname, surename and birthday is enough to identify blood:

• https://www.iakh.de/tl_files/iakh/public/register/2011/30-2011-l5i5-Beinaheverwechslung%20bei%20gleichem%20Namen%20und%20Geburtsdatum.pdf If there is a mistake that can be killing, in our case we have an issue for the support of the registration desk :-)