One could argue that the audience jjj has gone after, has predominantly been more of a left of centre group of younger people, based on its broadcasting structure. It likes to appeal to a left wing demographic, for whatever reason that may be. Maybe younger people are more generalised into an 'idealist', and or 'liberalized' section of society, rather than a more 'conservative' section of society, therefore jjj, by giving a poll to its primary demographic would actually be able to get a result it wanted. Acting as a whole, and asked to larger ABC audience, that my not have been the case. It acts as an 'arm' of the ABC, and should therefore act under the charter of the ABC as Wonganella pointed out.
With a 60 to 39 and 1 undecided result, aimed at its primary, and core demographic, would that of in fact have been enough, if the question was asked to a broader ABC audience? It does seem a rather slim victory, and possibly a dubious result, if the selected audience was chosen, and especially so if that did contravene any ABC charter guidelines. (And I m not aware fully of the charter, just making the proposition, it wasn't a fair poll in the first place, regardless if jjj think they can only asked their audience, are they charter bound to ask the wider ABC listener audience?)
