In my research it is suggested that there have been only 2 plebiscites in 1916 and 1917. Where does the national anthem question and same-sex marriage question fit?

Graphic of a blue rectangle being dropped into a larger blue box. This is repeated multiple times.

Ballot box graphic

Parliamentary Education Office (peo.gov.au)

Ballot box graphic

Graphic of a blue rectangle being dropped into a larger blue box. This is repeated multiple times.

Parliamentary Education Office (peo.gov.au)

Description

This graphic is a representation of a ballots being placed into a ballot boxes.

Yes, there have only been two plebiscites. A plebiscite is used to decide a national question that does not affect the Australian Constitution. The Australian Parliament decides how plebiscites are run. The national anthem question was a public opinion poll and the same-sex marriage question was a postal survey.  Both of these asked Australians what they thought about an issue but weren’t called plebiscites.