Citations are by nature heterogeneous. A citation worth may dramatically vary according to the influence of the citing article or to the journal's reputation from which it is issued. Therefore, while assessing the influence of an academic article, how should we weight citations to take into account their real influence? In order to answer this question, this article suggests various methods of weighting citations in the building of articles quality indexes. These indexes are then used to measure the influence of the articles published in the top five economic journals over the 2000-2010 period and analyses the sensibility of these indexes to the choice of the weighting schemes. Our main result is that whatever the weighting scheme, information carried by the different indexes is not significantly different. From Occam's razor principle, the number of citations provides an efficient and sufficient tool to measure research quality.