Primary Outcomes (explanation)
Social media activity: At the sender level, we measure the extent to which SMIs made posts with the treatment information, and the impressions and engagement their posts received. We similarly measure the impressions and engagement of Twitter ad posts with the treatment information received.
At the follower level, we measure the extent to which SMI followers posted, shared, replied to, and quoted others' posts. We refer to these forms of engagement collectively as ``posts'', since we are unable to distinguish between them for the subset of data scraped through traditional techniques following Twitter API's price changes.
Verifiable content: We trained a machine learning model to label followers' posts as verifiable or non-verifiable. Thanks to Africa Check's help labeling a sample of posts, we trained a binary classification model based on the Bidirectional Encoder Representations from Transformers (BERT) architecture. This model labeled posts as either verifiable or non-verifiable, and had a validation accuracy of 85%. Beyond being of interest itself, by identifying verifiable posts, we could subsequently label verifiable posts as fake or true, as we explain next.
Fake/true content: We developed an additional model to label followers' verifiable posts as either approximating content that is fake or true. This binary classification model was trained using posts labeled as ``fake'' by Africa Check in their fact checks or as ``true'' if they originate from reputable news sources, such as established newspapers. Similar to our verifiable model, we utilized the BERT architecture. Our model had a validation accuracy of 84%.
URL source: Since information and misinformation are often not explicitly written in posts, but shared through links, we analyze the URLs shared by followers. To do this, we first extracted all URLs from the posts and grouped them by domain name, and manually classified them as follows. First, we distinguish between links to information sources (e.g. newspapers, fact checks, blogs, etc.) versus other websites that do not provide information (e.g. gambling websites). Second, for information sources, we distinguish between reliable and non-reliable news websites, fact checks, and other information sources.
To categorize the news websites from Africa, we first leveraged a dataset from Africa Check that classified reliable and non-reliable new websites. Additionally, Africa Check reviewed and classified an extra batch of African news websites. For global news websites, we used several sources, including NewsGuard and MediaBias.
Topic sentiments: We analyze the effect of our intervention on the sentiment expressed by followers towards topics usually the subject of misinformation, such as COVID-19 and COVID-19 vaccines, and politics. We first identified and labeled tweets containing any information related to a given topic. For example, in the case of COVID-19 and COVID-19 vaccines, we manually defined a set of keywords, such as ``coronavirus'', ``COVID-19'', ``mRNA'', ``Pfizer'', etc., and filtered all posts containing these terms. From the subset of posts containing these keywords, we extracted the most frequent words (excluding the initial set of keywords) to ensure that no relevant terms related to the topic were excluded. We then identify the set of posts containing any of these terms.
We employ two different sentiment analysis models to predict the sentiment of each post as positive, negative, or neutral. Our primary analysis utilizes a BERT model, trained on a comprehensive dataset sourced from https://www.kaggle.com/datasets/datatattle/covid-19-nlp-text-classification, to perform sentiment prediction on the tweets. Additionally, for robustness, we consider https://vadersentiment.readthedocs.io/en/latest/, which is a lexicon and rule-based sentiment analysis tool specifically designed to detect sentiments expressed on social media.
Social interactions with follower content: We use data on the social interactions with the posts produced by followers to describe the popularity of each post that their own followers interacted with. We focus exclusively on original tweets, not retweets, as the API provides interaction metrics for the initial tweet in the case of retweets.
To conduct this analysis, we computed total interactions (likes, shares, comments, and retweets) with each follower's posts, as well as those specific to different types of posts (such as verifiable and non-verifiable posts) and posts with different sentiments about various topics (such as about COVID-19 and the COVID-19 vaccines).