Link to your statement?

The Australian Sports Commission has instituted a population tracking program, called AusPlay, to track sports and physical activities' participation in the Australian population. Latest published data I found are for the 12 months from October 2015 to September 2016. So about 12 months back. They were published in December 2016.

Based on those data, the participation rates among kids aged 0-14, for "organised out of school hours activities" were:

SPORT PARTICIPANTS % OF POPULATION
Swimming 1,378,967 30.0%
Football 674,094 14.7%
Australian football 366,462 8.0%
Gymnastics 341,200 7.4%
Netball 332,018 7.2%
Dancing (recreational)329,003 7.2%
Basketball 300,622 6.5%
Tennis 280,239 6.1%
Cricket 256,930 5.6%
Athletics (T&F) 203,873 4.4%
Rugby league 126,754 2.8%
Karate 121,877 2.6%
Dance Sport 106,901 2.3%
Hockey 76,922 1.7%
Touch football 76,039 1.7%
Lifesaving surf 65,986 1.4%
Fitness/gym 59,282 1.3%
Rugby union 57,429 1.2%
Taekwondo 49,261 1.1%
Martial arts 47,279 1.0%

So soccer was #2 and basketball was #7. If we focus just on team sports, soccer was #1 and basketball was #4, split by Aussie Rules and netball.

For boys' team sports, basketball was #4 behind soccer, Aussie Rules and cricket. For girls' team sports, it was #3, behind netball and soccer.

There's a separate table focusing in club sports for kids. I'll put that in a separate post.

Club sports' participation for kids aged 0-14:

Football 551,911 12.0% 28.8%
Australian football 328,540 7.1% 17.2%
Netball 271,559 5.9% 14.2%
Basketball 251,583 5.5% 13.1%
Cricket 203,168 4.4% 10.6%
Tennis 192,167 4.2% 10.0%
Swimming 191,038 4.2% 10.0%
Athletics, track and field 124,541 2.7% 6.5%
Rugby league 115,949 2.5% 6.1%
Gymnastics 109,802 2.4% 5.7%

So soccer still #1, basketball still #4, split by Aussie Rules and netball.

The AusPlay methodology is population sample based (20,000 adults in the sample, 3,600 parents of kids sampled).

Oh, the AusPlay data include adult data as well but the OP asked about kids. The relevant published reports can be found at http://www.ausport.gov.au/information/ausplay

These types of numbers are tough to come across. The relevant governing bodies generally have more accurate info than the ASC but will generally only release it on their terms and in a way that makes them look good.

AFL charts things like school visits and Auskick as participating. They have been falsely pumping their data for years. Just because an AFL player kicked a ball at you at school doesn't mean you play AFL.

On the flip side Basketball has done an absolutely horrible job historically of capturing data. Perhaps it has suffered for being too honest.

As noted these are numbers based on survey data. Other posters have noted the difficulties of numbers published by individual sporting authorities.

It's worth noting the sample sizes for this survey are good, as population surveys go. Also, the results, if I remember correctly, are consistent with the Australian Bureau of Statistics survey from 2-3 years ago. That suggests they're reliable population estimates.

"With the Aussie rules data take away watered down Auskick and numbers fall." Comparing the total and club sports' participation numbers shows just that difference for each of the sports.

"Those netball numbers can't be right being a one gender sport." The number of girls playing netball is almost the same as the number of boys playing Aussie Rules (324,000 and 320,000 respectively). I think that passes the sniff test.

"Basketball would be the number two sport for girls after netball ( team sports )" I assume you're saying the ASC numbers must be wrong. Those AusPlay numbers have soccer as #2 team sport for girls and basketball #3 (as per above post). FWIW, the respective participant estimates are 135,000 and 111,000, That 24,000 difference is much larger than the survey's margin of error.

An interesting question in my mind is whether there's a nexus between registration procedures and frequency of participation that could lead to multiple counting of participants. e.g., I've had a child competing simultaneously for two different teams/clubs in different "leagues" of the same sport - for one as a junior and another as a senior/open competitor. I've had this happen in team sport and in solo sport. Based on registration IDs, they'd have been counted twice by the sporting authorities concerned. If that phenomenon still exists and occurs materially more often for one sport relative to others, it would inflate participation numbers in a way that the AusPlay and similar surveys would avoid.

If a kid turns up for two hours a week to engage in an organised sporting program, I can't see how they're anything but a participant.

There are really 2 different ways of delivering programs like Auskick and Aussie Hoops.

The AFL fund Auskick programs in schools during school time or after school. The AFL also run Auskick through junior AFL clubs on weekends. 1 method involves kids doing a program at school with no local link to club (weekend) sport. The other involves AFL staff working with a local club's "Super 8s" coach/es. I've been involved in both, and the weekend/Super8s gets kids more involved with playing after the 8 week Auskick program concludes. A lot of kids sign up for a "school" Auskick program, pay the $60 or so and get about the same value in take away freebies (bag, hat etc).

Also if the fee is around $60 most of it goes to insurance. The AFL do really well out of the NAB sponsorship money to pay for coaches and freebies. Local clubs do get a benefit if people identify the club when signing up for a home loan. I don't remember basketball ever having such a sugar daddy to sweeten the deal and get little kids having a go. You can earn a few $ teaching kids the basics in AFL, but there's no money in basketball. Another aspect is the school ambassador programs giving teachers free tickets etc for being the "ambassador". In a rugby league dominated area, the AFL simply put more effort and $ in to developing strategic relationships in schools. This really pays off in raising awareness of a sport, developing both players and consumers/ viewers.

If basketball had a more significant schools program (and registered all participants) then they would be able to claim higher participation rates. Without the $, it would mean club coaches and older juniors coaching little kids in primary school settings. This is getting harder to do with working with children check requirements. This could be a role for lower tier imports, with clubs selecting imports with some form of teaching or coaching background in college.