It is very interesting to note that electoral enrolments, Australia-wide, increased by only a nett 9,026 enrolments between 30 June 2010 and the close of the rolls on 22 July 2010, if we disregard the 47,579 17-year-old provisional electors that presumably turned 18 during that 22-day interval.



Why do I disregard those 47,579 17-year-olds that turned 18?



I disregard them because, on the face of it, so many turning 18 in just 22 days seems statistically improbable.


See table of enrolments in this Twitpic: htthttp://twitpic.com/2exuj7

Source: http://www.aec.gov.au/Enrolling_to_vote/Enrolment_stats/elector_count/index.htm

From the tabulation, it does seem as if the sudden reduction of 47,579 in 17-year-old names carried on the rolls is to be accounted for by reason of them having turned 18, as the 18 & 19-year-old group shows a broadly concomitant increase of 43,350 names enrolled in the same 22-day period.

It is also to be noted that throughout the preceding year broadly similar numbers of 17-year-olds were shown as being enrolled at every quarterly date. Whatever the average number of days was that 17-year-olds spent on the rolls in that category, it did not seem to vary greatly over the year. A person only stays 17 for at most one year.

For each of those quarters it seems that 17-year-olds turning 18 were broadly speaking matched by 19-year-olds turning 20, as the 18 & 19-year-old total did not vary greatly over the year.

So what explains the concentration of 17-year-olds about to turn 18 between 30 June 2010 and 22 July 2010, 47,579 names, an average of 317 per Division if evenly spread?