Following the ABC's coverage of asylum-seeker claims of mistreatment by the navy, accusations of bias have been levelled at the broadcaster, and an efficiency review announced to assess its operations.

The prime minister, Tony Abbott, said the ABC took "everyone's side but Australia's" and should show "some basic affection for the home team". He also criticised the ABC for collaborating with Guardian Australia on reporting that Australian spy agencies had targeted the Indonesian president.

Conservative commentators have gone further, accusing it of being biased towards the left side of politics.

So, is the ABC biased?

Studies on bias are very thin on the ground, because measuring supposed bias is a very difficult business. To empirically determine what is factual, slanted, and misleading is challenging so we must look at a range of indicators.

Firstly, we can check if the ABC gives significantly more time to one side of politics during elections. Here's the time spent covering different political parties in the 2013 election:

2013 federal election coverage: cumulative share-of-voice, all platforms combined Radio TV Internet Total Hrs:Min:Sec % Hrs:Min:Sec % Words % % Coalition 55:27:29 37 37:10:23 43.4 27,588 39.7 39.4 ALP 51:52:10 34.7 41:53:43 48.9 29,079 41.9 40 Greens 14:51:44 9.9 3:57:37 4.6 6,069 8.7 8.1 Other 10:16:18 6.9 1:07:52 1.3 2,651 3.8 4.8 PUP 7:06:20 4.7 0:50:49 1 1,543 2.2 3.3 Independents 5:36:59 3.8 0:16:46 0.3 1,373 2 2.5 KAP 4:29:35 3 0:19:09 0.4 1,127 1.6 2 Total 149:42:35 100 85:36:19 100 69,430 100 100

Source: ABC, 2013 federal election. Report of chairman, election committee review panel

Coverage was pretty even between the two main parties, with Labor receiving 40% of coverage, and the Coalition 39.4%. In 2010, the split was similar:

2010 federal election coverage: cumulative share-of-voice, all platforms combined Radio TV Internet Total Hrs:Min:Sec % Hrs:Min:Sec % Words % % ALP 57:32:08 39.4 26:11:15 47.8 35,458 4.21 41.8 Coalition 57:40:08 39.5 24:00:59 43.9 37,917 45 41.2 Greens 16:18:24 11.2 3:17:24 6 7,217 8.6 9.6 Independent 7:24:17 5.1 0:57:24 1.8 2,175 2.6 4 Others 3:57:04 2.7 0:08:31 0.3 476 0.6 1.9 Family First 1:58:34 1.4 0:07:49 0.2 722 0.9 1 Democrats 1:00:57 0.7 0:02:16 0.1 215 0.3 0.5 Total 145:52:25 100 54:46:01 100 84,180 100 100

Source: ABC, 2010 federal election. Report of chairman, election committee review panel

Another way to approach the question of bias is by using public trust as a proxy. Newspoll conducts a survey commissioned by the ABC every year to gauge various aspects of audience satisfaction.

In the 2012-13 financial year, the "percentage of people who believe the ABC is balanced and even-handed when reporting news and current affairs" was 79% (PDF, page 30). While this is down slightly from early years (it was 83% in 2008-09), this is still an overwhelming majority.



A 2013 Essential poll on trust in different media organisations has ABC TV news and current affairs as the most trusted, with 70% saying they had total, a lot, or some trust in the ABC. Again, there was a small decline from the last poll, but almost all media organisations on the list had seen similar declines in trust.

Complaints are another measure of dissatisfaction with the ABC.

The famous 7:30 interview with Abbott by Leigh Sales accrued 523 complaints of anti-opposition bias. There were 2139 political bias complaints in 2012-13, meaning this one interview accounted for a quarter of all accusations of political bias.

However, Sales was cleared of political bias by the Australian Communications and Media Authority (Acma) and the ABC's audience and consumer affairs section.

Complaints have historically been split evenly between right and left viewer who feel their team is hard done by Aunty. During the 2003 invasion of Iraq there were 147 complaints of pro-US coverage and 144 complaints of anti-US coverage. On this Wayne Errington and Narelle Miragliotta wrote in 2011, "there appears not to be any factual evidence to back the claim of left-wing bias" at the ABC.

One more recent attempt to empirically measure bias was carried out by Joshua Gans and Andrew Leigh. It aggregated the top 100 public intellectuals mentioned in parliament and in the media from 1999 to 2007.

Intellectuals mentioned significantly more by Labor were weighted to the left and those by the Coalition to the right. For example, Mick Dodson and David Marr for Labor, and Marie Bashir and Paul Sheehan for the Coalition. These mentions were then used to estimate numerically an ideological position, using a score developed with binomial distribution analysis.

The researchers applied this scale to media organisations. A score of 0.47 on the scale is the midpoint between Coalition and Labor. Any score above 0.47 represents the media organisation giving more time to Coalition-favoured intellectuals, and below 0.47 represents more time given to Labor-oriented intellectuals.

Here are various media outlets scored using this method:

Media slant using public intellectuals Media Organisation Estimate Total mentions of intellectuals Australian Financial Review 0.44 1700 Canberra times 0.46 4916 Sydney Morning Herald 0.46 16,175 The West Australian 0.46 2352 Herald Sun 0.47 5073 The Age 0.47 10,499 The Advertiser 0.47 4485 ABC Radio National 0.47 1410 Daily Telegraph 0.48 5597 Sydney ABC 702 0.48 2249 SBS News 0.48 250 The Australian 0.48 16,934 ABC 891 Adelaide 0.49 590 Sydney 2UE 0.49 387 Perth ABC 720 0.49 483 Channel 10 News 0.49 275 The Courier Mail 0.49 6359 Melbourne ABC 774 0.5 972 Sydney 2GB 0.5 402 Brisbane ABC 612 0.5 489 Melbourne 3AW 0.51 234 ABC Channel 2 News 0.511* 940 Adelaide 5AA 0.51 257 Channel 9 News 0.52 423 Perth 6PR 0.52 251 Channel 7 News 0.52 269 Brisbane 4BC 0.52 142 Mean 0.48 3129 Note: * p=≤0.05

According to the Gans and Leigh study the only statistically significant slant was for the ABC Channel 2 News programme which preferences Coalition-favoured intellectuals in their reporting. This suggests the ABC news has a right-wing bias with a score of 0.511.

On to the question of efficiency. Here's the ABC's operation revenue from government, adjusted for inflation by indexing against CPI:



The greatest falls occurred under the Hawke government from 1985-86 to 1988-89 and Howard's government 1995-96 to 1997-98, which marks the lowest point in ABC funding in the last two decades.

In 2004 the conservative think tank McKinsey & Company compared funding of public broadcasters. Converted to 2004 Australian dollars by Errington and Mirragliotta, it found that in Germany, public broadcasting is funded at 80 cents per head, in Japan 45 cents per head, in the UK 59 cents per head and in Australia 23 cents per head.

If you compare the aggregate funding of the BBC to the ABC there is a much greater funding commitment to the BBC. The BBC has a budget of £5,102.3m (2013) which equates to AU$9,356.24m at today's rate of 1 GBP = 1.83 AUD. The UK has a population of 63.2 million people. Meaning for every million people in the UK there is $148.04 million in funds for the BBC. Compared with the ABC where there is only $1,221.2m (2013). Australia has a population of about 23.4 million. This means there is only $52.1m spent on the ABC for every million Australians. The BBC gets $148.04m per million head of population while the ABC gets only $52.1m.

Lastly, A KPMG report leaked in 2006 considered the ABC to be highly efficient and underfunded.

A section of the report, quoted in Crikey, said: "The ABC provides a high volume of outputs and quality relative to the level of funding it receives … the ABC appears to be a broadly efficient organisation."

These are the most comprehensive sources we could find on the topic in a short time frame, so please let us know in the comments if we've missed anything.

An earlier version of this post showed incorrect times for election coverage due to a formatting error (though the percentages were still correct). This has now been fixed.