Measuring Peer Review Quality Figure 3. Box plots for h index values of approved and rejected applicants for the LTF and YI programme. doi:10.1371/journal.pone.0003480.g003 committee made the right choice about who received funding. The higher productivity of the approved applicants against the rejected applicants may be because the committee made the right choice in deciding who should get funding but also be because they had funding allowing them (better) opportunities for research and subsequent publishing. There is circularity to this issue that should be considered in future studies investigating grant or fellowship peer review. To control in the statistical analyses for the influence of funding on subsequent publication and citation numbers, information is needed on funding of the rejected research by investigating the fate of the rejected applicants and their research projects. Peer review processes are never faultless. With the bibliometric data of the applicants subsequent to application we were able to calculate the extent of over- and under-estimation (type 1 and type II errors) of the future success of the applicants. We find that less than one tenth of all applicants were over-estimated (approved applicants who did not perform as well as or worse than the average rejected applicant), but approximately one third were under-estimated (rejected applicants who performed equal to or PLoS ONE | www.plosone.org 8 October 2008 | Volume 3 | Issue 10 | e3480