PMC:7386785 / 111984-112090 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T1329","span":{"begin":0,"end":106},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Could the reference standard, its conduct, or its interpretation have introduced bias?   Unclear risk  "}