Hits or the Long Tail? How Concentrated Is the Facebook Engagement of European Parties and Leaders, 2010 to 2020

Online attention is often described as a world of hits, in which a few items take most of the attention. Is the engagement that political parties receive on Facebook driven by a few viral posts, or spread across the many posts they make? I use 846,289 posts from 185 party and leader pages in 20 European countries between 2010 and 2020, collected through CrowdTangle, and measure how each page's engagement in each year was distributed across its posts. Engagement was concentrated, but not extremely: in the median page-year the top 1% of posts drew 8% of the interactions, the top 10% drew 36%, and the bottom half 18%, and the single most engaging post drew 2.8% in the median page-year and more than 10% in only 5% of page-years. The degree of concentration was similar for parties and leaders, populist and other parties, and parties in and out of government, and somewhat lower for pages with more engagement per post. Within pages, the share of the top tenth of posts rose by about 0.7 points a year to 2018, then fell. The rise holds with photo posts excluded, which allows for a May 2015 break in CrowdTangle's capture of photo posts, but most of it came as a step around 2015 rather than as a steady trend afterwards. The evidence on whether good years were driven by hits is mixed: depending on how extreme year-to-year swings are handled, the top tenth accounted for between 39% and 50% of the variance in changes, against a 38% share. The most engaging posts were more often videos and photos, less often links, and more likely to fall in the 30 days before a national election. The engagement parties receive on Facebook is better described as a broad base with a moderate head than as a market of hits.