positions accounts relative to each other based on the structure of their follower relations; densely interconnected accounts will form close clusters, while loosely connected accounts will be placed at a greater distance from each other.

Identifying the locations of the most active 10,000 ABC News and news.com.au sharers on this map, it is immediately obvious that those accounts which share links to ABC News are more predominantly concentrated in a cluster of accounts related to Australian politics, while news.com.au sharers are less prominent in this politics cluster, somewhat more prominent in a cluster relating to various sports, and more generally dispersed throughout the map. This clearly points to the very different information functions of these sites in the Australian public sphere in general, and in the Australian Twittersphere in particular -- functions which can be explained fairly directly by their divergent editorial directions.

The fact that these news outlets cater to and seek to attract different audiences may not be particularly surprising. What is notable, however, is that the social media analytics approach outlined here is able to detect the effects of such editorial positioning on actual audience engagement; this represents a new metric -- in addition to site visits, user registrations, and other data gathered by news organisations but rarely made publicly available in full -- which can be used to assess the relative market positioning of individual sites. The use of such external data (generated by and available from the Application Programming Interfaces (APIs) of social media platforms such as Twitter) provides an important opportunity for researchers to generate solid independent data on the performance of news outlets at least amongst specific social media communities; further, if demographic information on such communities is available, more general societal news engagement patterns may also be able to be extrapolated.

\section{Twitter News Audiencing Practices in Context}

One useful point of comparison in the Australian context is the data gathered by Experian Marketing Services, a company which captures anonymized information about the Web searching and browsing activities of some 1.5 million Australian Internet users. Its Experian Hitwise trends data, generated over the same timeframe as the ATNIX news sharing data and tracking the same set of news and commentary sites (with the addition of The Guardian and the Daily Mail), indicate that news browsing and news sharing practices in Australia differ considerably.

Fig.~\ref{fig:figure_2} compares the number of tweets linking to the ATNIX sites, as determined by the ATNIX data themselves, with the number of total visits to the same sites, as identified by Experian Hitwise, for the first quarter of 2015. The comparison shows a number of very significant differences in the ranking of the sites, which can be explained in large part by the specific demographics of Twitter in Australia, where the platform's core userbase remains centered around comparatively affluent, well-educated, and urban users in the 25--55 age range, even though a considerable number of teenage users have joined the platform since 2012 \cite{Sensis_2014,Bruns_2014}. Amongst the general population, middle-of-the-road news sites such as news.com.au and ninemsn News, UK tabloid spin-off Daily Mail Australia, as well as the site of quality newspaper Sydney Morning Herald are clearly leading the market -- but the news that Twitter users choose to share with their followers is predominantly sourced from quality outlets ABC News and Sydney Morning Herald.

\begin{table}[h]
\centering
\begin{tabular}{lr}
Website & Tweets \\
ABC News & 847,517 \\
Sydney Morning Herald & 811,222 \\
The Age & 356,255 \\
news.com.au & 266,323 \\
The Australian & 202,326 \\
The Conversation & 186,418 \\
Herald Sun & 153,966 \\
SBS World News & 143,589 \\
Daily Telegraph & 133,319 \\
\end{tabular}
\label{table_1}
\end{table}

\begin{table}[h]
\centering
\begin{tabular}{lr}
Website & Total Visits \\
news.com.au & 165,271,547 \\
Sydney Morning Herald & 114,343,374 \\
Daily Mail & 88,598,701 \\
ninemsn News & 75,772,762 \\
The Age & 73,188,461 \\
ABC News & 65,723,995 \\
The Guardian & 40,418,969 \\
Herald Sun & 38,987,455 \\
Courier-Mail & 36,795,376 \\
\end{tabular}
\label{table_2}
\end{table}