x 10 9 may be x 10⁹, chi 2 5 may be chi-squared with five degrees of freedom, and 1 2 may be one half. Read any expression here against the published paper before relying on it.phenomenon · claim-type · cross-domain-transfer · mechanism · claim-relation · replication-status · limitation — grounded in the full text| phenomenon | political echo chambers on social media— “This paper studies the phenomenon of political echo chambers on social media.” | |
| claim-type | existence— “When applied to discussions about politically contentious topics, our results support the existence of political echo chambers.” | |
| method — evidence | — “We use a collection of ten different datasets from Twitter, each of which contains a set of tweets on a given topic of discussion.” | |
| mechanism | content and network are measured JOINTLY at the level of the individual user, rather than content consumption alone, and the authors state that as the study's distinguishing move— “Unlike many previous works that focus on measuring only content consumption to quantify the echo-chamber effects, we study content consumption and production jointly at the level of individual users, and examine how different content profiles correlate with the network position of users. Though we are not the first to study echo chambers on… | mechanisms[0] |
| mechanism | POLITICAL LEANING IS NOT INFERRED FROM THE TEXT AT ALL: scoring short snippets is called very challenging, so the leaning is inherited from an externally supplied per-domain ground truth of news organisations— “Obtaining a characterization of political leaning for short text snippets, such as tweets, is a very challenging problem, in general. To confront this challenge, we use a ground truth of political leaning scores of various news organizations with” | mechanisms[1] |
| mechanism | and that borrowed score has a stated meaning of its own - the FRACTION OF FACEBOOK USERS VISITING A DOMAIN WHO IDENTIFY THEMSELVES AS CONSERVATIVE ON THEIR PROFILE - which the authors read as the domain having a conservative or liberal bent in its coverage— “The score takes values between 0 and 1 and expresses the fraction of Facebook users who visit these pages that identify themselves as conservative on their Facebook profile. A value close to 1 (0) indicates that the domain has a conservative (liberal) bent in their coverage.” | mechanisms[2] |
| mechanism | the measurement is deliberately restricted to what can be scored: only tweets carrying a link to a news organisation with a known and independently derived leaning are counted at all— “To quantify the political leaning of content posted on Twitter, we consider only messages that contain a link to an online news organization with a known and independently derived political leaning. In particular, we use the dataset of the political leaning scores of news organizations described in Section 3.” | mechanisms[3] |
| mechanism | CONSUMPTION IS DEFINED THROUGH THE NETWORK: a user's produced content is the tweets they post, and their consumed content is the tweets posted by the accounts they follow— “For the content production of a user u, we consider tweets posted by user u. For the content consumption of a user u we consider tweets posted by users whom u follows.” | mechanisms[4] |
| mechanism | partisanship is given a PARAMETERISED definition rather than a threshold - a user is delta-partisan when their production polarity lies within delta of either extreme - and the authors state the nesting property that follows, so a claim at one delta implies the claim at every larger one— “We say that a user is δ -partisan, for some value 0 ≤ δ ≤ 1 2 , if their production polarity is within δ from either extreme value min{p(u), 1 − p(u)} ≤ δ . (2) The smaller the value of δ the more partisan a user is. Note also that if a user u is δ -partisan then u is also δ ′-partisan for δ < δ ′ ≤ 1” | mechanisms[5] |
| mechanism | VARIANCE IS MEASURED ALONGSIDE THE MEAN over the same set of tweets, with the stated objective of quantifying the RANGE of opinions a user's produced content covers— “Besides the average political leaning of produced tweets, we also measure the variance in political leaning over the same set of tweets. The objective is to quantify the range of opinions of a user covered by the produced content.” | mechanisms[6] |
| mechanism | FIVE NON-POLITICAL DATASETS ARE COLLECTED AS A BASELINE for the political ones - tbt, ff, gameofthrones, love, foodporn - each built from one hashtag by parsing an archive, filtering to users with at least five tweets, and then taking all of those users' tweets— “To have a baseline for our measurements over the Political datasets, we also use five datasets that correspond to non-political topics, in particular: tbt (“throwback Thursday”), ff (“follow Friday”), gameofthrones, love, and foodporn. Each of these topics is associated with a particular hashtag (e.g., #tbt for tbt). The datasets are built as… | mechanisms[7] |
| mechanism | automated accounts are excluded by minimum AND maximum thresholds on tweets per day, followers and friends, together with a requirement that the account be at least one year old at collection time— “For all the datasets, we perform simple checks to remove bots, using minimum and maximum thresholds for number of tweets per day, followers, friends, and ensure that the account is at least one year old at the time of data collection.” | mechanisms[8] |
| mechanism | the paper STIPULATES 'gatekeeper' against the established sense and says so: in communication studies the term names news media sources acting as filters, and here it names an individual user who receives content from both leanings but produces only one— “Gatekeeping is a term commonly used in communication studies to refer to news media sources that act as filters of information [27]. Barzilai-Nahon [8] propose a model based on network theory for gatekeeping which generalizes the concept of gatekeeping for the Internet and applies to all information types (not just news). Several studies have… | mechanisms[9] |
| extends | the study of political polarization and echo chambers— “The results shown in this study are just one step towards the understanding of echo chambers and the interplay between network and content, which open up several directions for future work.” | claim_relations[0] |
| builds-on | the latent space model of Barberá et al. [7]— “We adopt the latent space model proposed by Barberá et al. [7] to estimate a user polarity score.” | claim_relations[1] |
| builds-on | the news-source leaning scores and hard/soft news classifier of Bakshy et al. [4]— “During preprocessing, we attempted to split news articles from these sources into hard (politics, opinion, etc.) and soft news (gossip, entertainment, etc.) and applied the classifier from Bakshy et al. [4].” | claim_relations[2] |
| replicates | Barberá [6] on higher polarization of retweet networks for political topics— “This result reinforces the validity of the proposed measures — and agrees with similar conclusions presented by Barberá [6], where retweet networks exhibit higher polarization for political topics.” | claim_relations[3] |
| extends | prior echo-chamber studies that measure either content or network alone— “In this paper, we propose measures to identify the existence of an echo chamber by using both the content being read/shared and the network that enables the content to propagate.” | claim_relations[4] |
| sense | an echo chamber - AS AGREEMENT BETWEEN TWO PER-USER SCORES: it exists, for this paper, when the leaning of the content a user receives agrees with the leaning of what they share; not a group, not a network structure, not an isolation measure, but a correlation computed per user - and the authors adopt it because the literature offers no consensus formal definition to inherit— “We say that an echo chamber exists if the political leaning of the content that users receive from the network agrees with that of the content they share. As there is no consensus on a formal definition in the literature, we opt for this definition, which is general enough and reasonably captures the essence of the phenomenon” | senses[0] |
| sense | a gatekeeper - AN INDIVIDUAL USER, NOT A MEDIA SOURCE: communication studies gives the word to institutions that filter what passes into a channel, and this paper reassigns it to a person at a particular position on two scores, stating the earlier sense and supplying a bridging argument - that such users block information from one side, and hence can be considered gatekeepers— “Gatekeepers are defined in media and communication studies as media sources that act as filters (or ‘gatekeepers’) of information [27]. In our case, we consider consumption and production of content jointly, and define gatekeepers as users who consume content from both… | senses[1] |
| sense | leaning - A STIPULATED SCORE, WITH ITS OWN SYNONYMS NAMED IN THE FOOTNOTE THAT STIPULATES IT: the authors define it as a score quantifying alignment with one political side and list the terms the literature uses for the same thing, so four words - leaning, ideology, polarity, ideological stance - are declared interchangeable by the paper itself | senses[2] |
| control | ten-fold cross-validation of the partisan and gatekeeper classification model — held — rules out an accuracy figure earned on the same data the classifier was fitted to | controls[0] |
| edge | echo chamber —operationalised-as→ leaning Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concept_edges[0] |
| audit | gatekeeper —contrasted-with→ media sources — Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span defines gatekeepers differently in media studies and in this study; contrasted-with is a loose reading. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concept_edges[1] |
| outcome (stated by the tagger, no quotation) | control — held | controls[0] |
| for which use | limitation — every political-leaning measurement in the study: WE CONSIDER ONLY MESSAGES THAT CONTAIN A LINK TO AN ONLINE NEWS ORGANIZATION WITH A KNOWN AND INDEPENDENTLY DERIVED POLITICAL [leaning] - users without such links are unmeasured Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[0] |
| for which use | limitation — the generalisation to political discourse at large: all data come from Twitter and are only a sample of social-media discussion Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[1] |
| for which use | limitation — the network measured: the analysis rests on the retweet and follow graph available through the API, not on the full communication structure Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[2] |
| for which use | limitation — every polarity score: OUR PRODUCTION AND CONSUMPTION SCORES RELY ON EXTERNAL LABELING OF NEWS SOURCES ALONG A POLITICAL AXIS Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[3] |
| for which use | limitation — every consumption measure: OUR ANALYSIS ASSUMES THAT EACH USER CONSUMES ALL CONTENT PRODUCED BY ALL THEIR NEIGHBORS - following stands in for reading Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[4] |
| for which use | limitation — the political-content assumption: NOT ALL NEWS ARTICLES FROM THE NEWS SOURCES WE BASE THE POLARITY MEASURES [on] ARE POLITICAL Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[5] |
| for which use | limitation — any causal reading of echo chambers: UNDERSTANDING HOW ALL THESE PHENOMENA INTERACT WITH EACH OTHER AND THE PRECISE CAUSALITY RELATIONS IS BEYOND THE SCOPE OF THIS PAPER Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[6] |
| for which use | limitation — the finding that echo chambers are prevalent: the authors state there is no consensus on a formal definition of an echo chamber in the literature and opt for their own, under which an echo chamber exists when the leaning of content a user receives agrees with the leaning of what they share Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[7] |
| for which use | limitation — any comparison with the gatekeeping literature: in media and communication studies gatekeepers are media sources acting as filters, whereas here they are individual users identified by their joint consumption and production leaning Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[8] |
| for which use | limitation — the gatekeeper results reported here: the authors also tested a different definition - high consumption variance with low production variance - found the results almost identical, and did not present them explicitly Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[9] |
| for which use | limitation — any interpretation of the gatekeeper class: the authors say it is not clear from their analysis what such users are doing, so the label marks a position on two measures and not a motive Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[10] |
| evidence status note | mechanism — 2026-08-16: THIS QUOTE IS TRUNCATED MID-SENTENCE BECAUSE THE FILE INTERRUPTS IT. The staged text continues "...news organizations with 6https://en.wikipedia.org/... 7http://www.bbc.com/... 8https://www.nytimes.com/..." - three footnote URLs are spliced between 'with' and the rest of the clause, which resumes as 'a presence on social media obtained from Bakshy et al.' The span stops at the last word before the splice. The sentence is not quotable in full from this file without quoting three URLs in the middle of it. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | mechanisms[1] |
| replication | untested | |
| no type for this | follow → content consumption — THE INDEXING / PROXY RELATION - 'from' STANDS IN FOR 'to'. We have no type for it: 'causes' asserts production, and 'operationalised-as' says the authors CHOSE a measure, whereas a proxy claim says THIS STANDS IN FOR WHAT WE ACTUALLY CARE ABOUT AND WE KNOW IT IS NOT THE SAME THING. Measured at 8% of papers. A measurement substitution stated plainly: 'we use the “follow” relationship as a proxy for the actual content consumption'. The word 'actual' is doing the same work as amodei2016's 'really care about' - the authors marking the distance between what they measured and what they meant. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | unhoused_relations[0] |
| limitation | political leaning is measured only from tweets that link to news sources of known, independently-derived leaning, not the message content itself Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[0] |
| limitation | All data come from Twitter and are only a sample of social-media discussion. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[1] |
| limitation | Results are drawn from politically-savvy users and should not be assumed to generalise to the general public. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[2] |
| limitation | The polarity measures depend on externally supplied political labels for news sources. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[3] |
| limitation | Following is used as a proxy for actual consumption; users may not read everything their neighbours post. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[4] |
| limitation | Some articles from the scored news domains may not be political. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[5] |
| limitation | The causal relations between selective exposure, biased assimilation, algorithmic filtering and echo chambers are not addressed. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[6] |
| limitation | The literature has no consensus definition of the paper's central term, so the authors chose one. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[7] |
| limitation | A term is borrowed from another field with its unit of analysis changed, which the authors state. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[8] |
| limitation | A second definition of the same category was tested and its results not presented. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[9] |
| limitation | What the identified users are actually doing is left open by the authors. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[10] |
finding · quantity · variable · definition · key-term — grounded in the full text| finding | Twitter users mostly see political opinions matching their own. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[0] |
| finding | Engagement is measured as all content that a user clicks. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[1] |
| variable | political leaning (independent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[0] |
| definition | echo chamber Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[0] |
| evidence status note | definition — QUOTE REPAIRED: the extractor split a hyphen-space and the quote was recorded faithfully with the damage in it, which made it unanchorable. The repaired string is an EXACT SUBSTRING of the staged text - that is why it was accepted, not because a rule produced it. The text as originally recorded is kept in evidence as extracted. | content_tags.definitions[0] |
| definition | production Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[2] |
| definition | consumption Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[3] |
| definition | engagement Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[4] |
| key-terms | echo chamber, users, political, network, Twitter, opinions, partisan, discourse, engagement |
| concept | echo chamber Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[0] |
| concept | gatekeeper Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[4] |
| concept | media sources Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[5] |
| concept | leaning Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[6] |
| concept | consumption variance Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[7] |
| concept | price of bipartisanship Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[8] |
| correlation r | as written: correlated Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[1] |
| evidence status note | correlation — QUOTE RECOVERED FROM THE PAPER'S OWN CHARACTERS. The recorded quote was LETTERS-ONLY IDENTICAL to this stretch of the staged text but not an exact substring of it - spaces, hyphens, ligature glyphs or mathematical operators differed, so it could never anchor. This is the file's own text between the same two letters: not produced by a rule about the damage, copied out of the file. Round-trip checked (the recovered span is letters-only equal to the original) and length-checked. The text as originally recorded is kept in evidence as extracted. | content_tags.statistics[1] |
| effect-size d | Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[2] |
| p-value p | as written: p < 0.001 Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[3] |
| evidence status note | p-value — QUOTE RECOVERED FROM THE PAPER'S OWN CHARACTERS. The recorded quote was LETTERS-ONLY IDENTICAL to this stretch of the staged text but not an exact substring of it - spaces, hyphens, ligature glyphs or mathematical operators differed, so it could never anchor. This is the file's own text between the same two letters: not produced by a rule about the damage, copied out of the file. Round-trip checked (the recovered span is letters-only equal to the original) and length-checked. The text as originally recorded is kept in evidence as extracted. | content_tags.statistics[3] |
| statistical-significance | as written: statistically significant Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[4] |
When we have changed our mind. Some entries in the table begin with a word in capitals and the reason for it. EVIDENCE CORRECTED — the finding still stands, but we had quoted the wrong sentence from the paper, and the quotation has been replaced with the right one. RETRACTED — the entry itself was wrong; it stays on the page, marked, with the reason, rather than being deleted. WITHDRAWN AND REPLACED — the entry was wrong, and a corrected version of it appears in the entries below. Each mark carries its own reason, in brackets, because the reasons differ from one entry to the next. An entry we have WITHDRAWN is removed from this page and kept in the record, with its reason. A line reading Audit and a date is a later re-reading of the entry against its whole sentence: DOUBTFUL means it was kept, and the reason says what is loose about it. Quotation marks inside the tagger's sentence. Where a tag is the tagger's own sentence, a phrase in quotation marks inside it is borrowed from the paper — the tagger's wording around it is not. The paper's own sentence is the evidence quote for that row; on this page it is withheld with the article, and the article is at its publisher. Nothing inside quotation marks anywhere on this page is ours: if it is quoted, it is the paper's. Whose words a concept carries. A concept entry records a term the paper itself uses, so the term, the sense given for it, and its evidence are the paper's own words, quoted where the paper fixes them. This is the opposite of a sense entry in the tag table, which is the tagger's sentence about how the paper uses a term. Where a concept entry could not be grounded in the paper's words, the entry says so on its own row.
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