A question of considerable interest in a world of tightened resources is the relationship between research outputs to research inputs. At the national level, policy makers want to know the degree to which more funding leads to more research. At the micro level, funding agencies want to know the degree to which research can be attributed to the funds invested in researchers. These types of questions are sometimes answered by relating the amount of direct funding investigators receive from a foundation or agency to the number of articles published in the next two or three years.
The approach of relating publications to agency funding (PAF) highlights two issues encountered in examining the relationship between research inputs and outputs. The first is one of attribution: exactly which articles should be attributed to what funding stream? In the PAF approach all articles published in the next few years are attributed to total agency funding received in a given year. Yet some articles undoubtedly result from funding received prior to the year being studied while others relate to funding received in future years. The PAF approach also assumes that all articles can be attributed to funding from one agency. Yet many researchers have funding from more than one agency.