Field of application/theoretical foundation: Analyses of actor diversity are theoretically linked to news performance and the democratic media function of integration (Imhof, 2010). This construct is related to the normative assumption that news content should represent society as a whole and thus cover a large variety of societal groups (Boydstun et al., 2014). More recent studies also focus on the influence of algorithms on news diversity (Möller et al., 2018). Analyses are often carried out in three steps. First, all actors are (inductively or deductively) identified. Second, actors are coded according to predefined lists. Third, the level of diversity is determined using diversity indices (van Cuilenburg, 2007). Diversity indices are calculated at article level (internal diversity) or at the organizational level (external diversity) to compare diversity between news articles of a single outlet or between different news outlets. References/combination with other methods of data collection: Studies on actor diversity use both manual and automated content analysis to investigate the occurrence of actors and in texts. They use inductive or deductive approaches and/or a combination of both to identify actor categories and extend predefined lists of actors (van Hoof et al., 2014). Example studies: Masini et al. (2018); Humprecht & Esser (2018) Table 1. Summary of studies on actor diversity Author(s) Sample Unit of Analysis Values Reliability Masini et al. (2018) Content type: news about immigration Outlet/ country: 2 news outlets in four countries (BE, DE, IT, UK) Sampling period: January 2013 to April 2014 Sample size: N=2490) Unit of analysis: news article No. of actors coded: max. 10 quoted or paraphrased actors per article Level of analysis: article and news outlet level Diversity measure: Simpson’s diversity index National politics, international politics, public opinion and ordinary people, immigrants, civil society, public agencies/ organizations, judiciary/police/military, religion, business/corporate/finance, journalists/ media celebrities, traffickers/smugglers Krippendorff’s alpha average ?0.78 Humprecht & Esser (2018) Content type: Political routine-period news Outlet/ country: 48 online news outlets from six countries (CH, DE, FR, IT, UK, US) Sampling period: June – July 2012 Sample size: N= 1660 Unit of analysis: Political news items (make reference to a political actor, e.g. politician, party, institution in headline, sub?headline, in first paragraph or in an accompanying visual) News items are all journalistic articles mentioned on the front page (‘first layer’ of the website) that are linked to the actual story (on second layer of website) No. of actors coded: Max. 5 main actors (mentioned twice) per news item measured Level of analysis: news outlet level Diversity measure: relative entropy Executive (head of state and national government), legislative (national parliament and national parties), judicial (national courts and judges), national administration (prosecution, regional government authority, and police or army), foreign politicians (foreign heads of state and other foreign politicians), and international organizations (supranational and international organizations) Cohen’s kappa average ?0.76