As part of my doctorate, I'm researching the political independence of public service broadcasters. This is a difficult concept to define, much less measure. One approach is to ask people whether they perceive the broadcaster to be independent - or impartial, or biased. (The latter two are very different to the former, but may be an acceptable proxy, since polls show that media attitudes are largely covarying). This Roy Morgan Research Poll looks at perceived bias in Australia.
The poll is an example of how to approach this problem badly.
First, the relatively small sample size of 700 pushes the margin of error up to 4%.
Second, some of the questions can't be interpreted without controls. For example: how are we supposed to interpret the fact that relatively few people think internet news biased - when we don't know how many of the sample regularly use the internet or have any familiarity with it?
Third, the poll uses broad categories: newspaper journalism, television journalism, and 'talkback radio'. There is nothing intrinsically wrong with this; but it doesn't help with answering the important question of whether ABC is biased, or whether some newspapers are biased - for example, those owned by Murdoch, or by Packer.
Fourth, the poll makes extensive use of open response questions, such as inviting individuals to name reporters they think biased. This prevents comparability over time and space, and may deliver misleading results if respondents name merely those respondents they are most familiar with.
Fifth - and evidence that the poll is, at best, pitched to increase interest in its findings, or, at worst, a push poll funded by interested parties (there's no info on the commissioning party) - the poll asks about left-wing bias, but doesn't ask about right-wing bias. Some might say that it is self-evident that there is more danger of left-wing bias than right-wing bias. But this is not at all self-evident, and asking questions about both types of bias would in fact help to confirm or disconfirm this presumption. Certainly, BBC polling in the early nineties found that more respondents thought the BBC was biased towards the (right-wing) government than the reverse.
We can say, however, that television tends to come off better than the printed word. This is unsurprising: regulation of poltiical content on television tends to be stricter than that applied to the press; the printed word has more regulatory room to be biased.
There isn't much that is specific to ABC: one reporter identified as biased comes from ABC (compared to three from Nine); and 0.5% of the sample believe ABC News as a whole to be left-leaning. But, again, without asking separate questions about different news outlets, these results are of little worth.
I understand from this page that ABC commissions polls on this - but it makes the same mistakes - on the crucial issue of 'being balanced' it has no comparison with other broadcasters, merely comparisons over time.