This paper studies the citation decision of a scientific author. When an author can makehis argument more persuasive by citing a related work, this is called the correlation effect.On the other hand, when an author cites someone else’s work, he gives the impression that heviews the cited author as more competent than himself; this is called the signaling effect.These two effects are the main causes of citation bias. Using data from Research Papers inEconomics or RePEc, a decentralized database of working papers, journal articles andprofessional books, we empirically show that a citation bias exists in this field. The empiricalfinding is obtained by controlling for many variables that affect citation patterns, such asnetwork factors (co-authorship and an author’s affiliation) and language.