title: Two-year citations of JAPPL original articles: evidence of a relative age effect.
abstract: Several indicators have been used to analyze scientific journals, with the impact factor and the number of citations in a 2-yr calendar time frame (2-YRC) being the most common factors. However, considering that the Journal of Applied Physiology (JAPPL) appears monthly and that calculations of these indicators are based on citations of papers published in previous years, we hypothesized that articles published at the beginning of the year would be cited more in the 2-YRC compared with those appearing in the last issues of the year, a phenomena known as a relative age effect. Our objective was to confirm the existence of a relative age effect in the 2-YRC for original articles published in JAPPL. From 2005 to 2008, a total of 1,726 original articles were published, according to the Web of Science, and 9,973 citations in 2-YRC, varying from 0 to 45, with a mean of 5.78 for individual papers. Although there were no differences in the number of original articles published in a given month (P = 0.99), the 2-YRC varied considerably throughout the year, being higher for those earlier issues of the year, as shown by the linear regression analysis (r(2) = 0.76; P < 0.001). The 2-YRC began at 6.62 during the first 3 mo of the year, dropping by 10% at each 3-mo period. In summary, the longer an article has been out there, the more citations it collects. The relative age effect is a potential confounding variable for the assessment and interpretation of 2-YRC (using calendar years) from JAPPL original articles.
authors.affiliation: Exercise and Sport Sciences Graduate Program-Gama Filho University, RJ, Brazil. cgaraujo@iis.com.br
authors.forename: Claudio Gil
authors.initials: CG
authors.lastname: Soares de Araújo
authors.forename: Claudio Gil Soares
authors.initials: CG
authors.lastname: de Araújo
authors.forename: Bruno Ribeiro
authors.initials: BR
authors.lastname: Ramalho de Oliveira
authors.forename: Bruno Ribeiro Ramalho
authors.initials: BR
authors.lastname: de Oliveira
authors.forename: Letícia Vargas
authors.initials: LV
authors.lastname: de Oliveira Brito
authors.forename: Thiago Torres
authors.initials: TT
authors.lastname: da Matta
authors.forename: Bruno Ferreira
authors.initials: BF
authors.lastname: Viana
authors.forename: Cintia Pereira
authors.initials: CP
authors.lastname: de Souza
authors.forename: Renato de Carvalho
authors.initials: RC
authors.lastname: Guerreiro
authors.forename: Renato
authors.initials: R
authors.lastname: de Carvalho Guerreiro
authors.forename: Fabian Antonio
authors.initials: FA
authors.lastname: Slama
authors.forename: Eduardo da Matta Mello
authors.initials: ED
authors.lastname: Portugal
authors.forename: Eduardo
authors.initials: E
authors.lastname: da Matta Mello Portugal
mesh_terms: D015706:Bibliometrics; D035843:Biomedical Research / Q000706:statistics & numerical data*; D015986:Confounding Factors, Epidemiologic; D055811:Journal Impact Factor; D016014:Linear Models; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D010827:Physiology / Q000706:statistics & numerical data*; D013997:Time Factors