Balloting is required when the number of applicants is more than the vacancies. But it is not a random selection from all the applicants. Instead, applicants are grouped based on 2 factors:
Applicants are put into 6 groups in this priority:
Singapore Citizens (SC) have higher priority than Permanent Residents (PR), along with home-school distance advantage. The home address is that of the parents and you can check the exact radius on OneMap.
The places are given out in a waterfall manner.
For example: If vacancy is 15 and there are 10 applicants in Group (1), then all 10 applicants will have a place, and 5 vacancy will be left for Group (2). If Group (2) has 10 applicants, then they will have to ballot for the 5 places. Only Group (2) is involved in the balloting. Group 3-6 don’t even get to ballot.
Watch this video for an explanation.
In the ballot history, we use shorthand symbols to denote which group requires balloting. They correspond to the 6 groups.
It gets more complex because there can be no balloting even when there are more applicants than vacancy. This happens when the waterfall has no leftover for the next group.
There are 5 such borderline cases, which we append a # to denote.
|7.||SC<1#||SC < 1km all admitted, with no leftover|
|8.||SC<2#||SC < 2km all admitted, with no leftover|
|9.||SC#||SC all admitted, with no leftover for PR|
|10.||PR<1#||PR < 1km all admitted, with no leftover|
|11.||PR<2#||PR < 2km all admitted, with no leftover|
So in total there are 11 ballot symbols, and they give you a good gauge where balloting could occur for a phase.