I have been entering the ballot for 13 years now and at the end of the day its down to three things
1/ Predicted finish time
2/ Number of times rejected in last 5 years
3/ Number of times excepted in last 5 years
It has nothing to do with where you live, your occupation, or what you do for a living as some people have suggested. Up until last years if you were rejected you actually got the whole application back unopened. So they only know 3 things from the outside of the envelope
My theory is that it has to do with the predicted finish time, I read an article a long time ago by Dave Bedford who stated that it is important to get a constant flow through the finish. Therfore they need to put in so many from each time slot going in quarter hour slots as per the application form. After they have all these then I think it goes down to point 2 and 3. I envisage that all the time categories and laid out in massive 'blocks' and a certain amount are selected from each - after that they maybe selected from points 2 ansd 3 or maybe not I am unsure of that
Certain about point 1 though - and if you think about it it wiould be chaos if they had 3k finishing between 3:45 - 4:00 and 500 between 4:00 and 4:15 which fesably could happen if the did not take into account peoples finishing time
However having said that I am sure there are many more people applied stating they will finish in under 3 when they know they will take 5 hours so as carefull as they can be about the constant flow I am sure there is every possibility it will go awry