Gen Con Indy, America's biggest (non-electronic) game convention, which had its four-day run in August (see 'GenCon Wraps Third Indy Convention'), announced record turnstile attendance (person-days) of 82,121.  Over 25,000 unique individuals attended the show. 

We asked Gen Con CEO Peter Adkison to help us understand the numbers, and he walked us through the difference between 'turnstile' attendance and unique attendees. 

'This year our turnstile attendance was just over 82,000 and our estimate on unique attendance was just over 25,000.  The number of badges sold was over 28,000; some of those are 4-day badges and some are 1-day badges.

 

To get turnstile we take the 4-day badges and multiply by four and add the 1-day badges to that number.  The reason unique attendance is slightly less than the number of badges sold is that there is a corner case of when someone comes for exactly two days they buy two 1-day badges.  If someone comes for 1, 3, or 4 days, they buy just one badge (1-day or 4-day).  (A person who comes for 3 days buys a 4-day badge because it's cheaper than 3 1-day badges.)

 

Unfortunately we have no way of knowing exactly how many people came for exactly two days.  So we estimate it.  If no one came for exactly two days, than the unique attendance would equal badges sold.  If everyone who purchased at least one one-day badge came for exactly two days, than the unique attendance would equal the number of 4-day badges sold plus half of the one-day badges sold.

 

Reality is somewhere in the middle.

 

So we estimate unique attendance as the half-way point between these two possible extremes.'

We asked Adkison to help because we were having trouble comparing the 2005 numbers to 2003, in particular, which reported attendance of 28,000 (see 'Attendance Up at Gencon Indy').  Adkison explained that the way Gen Con counts its attendees has changed since 2003.  'The reason our attendance looks like it dropped is because for many years Gen Con reported 'attendance' at, simply, the number of badges sold,' he said.  'Eventually I figured out the system well enough to realize that this wasn't very honest and at that point changed our reporting methodology.'

Adkison explained that the 'turnstile attendance' in 2005 was a record, tying 2003 for number of unique attendees.  'For unique attendance this was about tied with 2003 as the best Gen Con since we acquired the show,' Adkison explained.  'I'd call it a 'record attendance' on a turnstile basis, as a higher percentage of the attendees stayed for four