From the author of a new media bias data site:
I am a self-employed Computer Scientist with a PhD in Computer Science from the University of Auckland and have been working in the field of robotics, machine learning and data science for the last several years.
I thought you might be interested in a project that I’ve been working on for the past four months; a service that automatically measures political bias in the New Zealand media, using a machine learning model that evaluates the sentiment of sentences (from news articles) which mention MPs and political parties.
The website is available here: mediabias.co.nz
Whilst the results are preliminary, as far as I’m aware, it is the largest automated analysis of political bias in the New Zealand media to date. The analysis currently covers ~380,000 sentences from ~65,000 political news articles that were published over the past year in 15 media sources and popular New Zealand political blogs (including Kiwiblog). I have included political blogs in the analysis to get a rough idea if the system is working. Although not perfect, the current results do appear to show that the New Zealand media are heavily skewed to the left in terms of political sentiment. There are limitations with the analysis (these are described in more detail on the website), the main one being that the analysis was performed on articles published when the Labour Party was in power, the results may change somewhat if performed on articles published when the National Party was in power.
If you go to the website, you can click on individual media sources in the table to view more details, including a chart with a breakdown of how biased the media source is to each political party and a time-series chart of the sentiment for each party plotted over the course of a year. The results look best if you view it on a desktop or laptop as I haven’t had enough time to optimise it for mobiles yet.
The site describes the methodology:
Ingest news articles: collect articles from New Zealand media sources.
Filter news articles: automatically select articles that discuss New Zealand politics.
Entity & Sentiment Analysis: extract references to members of parliament (MPs) and political parties from article text and analyse the sentiment of each sentence.
Party Bias Calculation: party bias is measured by taking the mean bias error (MBE) between the given party and all other parties, for a particular media source.
Media Bias Calculation: for a particular media source, the mean of the absolute MBE score for each party is taken.
Coverage Calculation: the sum of all times that an MP of a particular party or the party itself are mentioned in articles published by a particular media source.
Political Leaning Calculation: MBE between all left-wing parties and all right-wing parties.
The site finds Politik to be the least biased site and excluding blogs, Newshub and Scoop to be the most.