Modeling the length and shape of the R&D lag: an application to UK agricultural productivity
更新了1953-2005年英国农业全要素生产率增长数据，发现公共和私人研发及规模报酬可解释TFP，并比较了数据决定滞后与常见固定滞后对研发回报率的影响。
Abstract This article updates total factor productivity (TFP) growth in UK agriculture from 1953–2005 and shows that public and private research and returns to scale explain TFP. Cointegration and causality tests are used to investigate the validity of attempts to explain UK agricultural productivity with R&D and related technology variables. Then, the length and shape of the lag structures are modeled and compared with the structures that are commonly imposed on the data. The rates of return (ROR) to R&D using the data determined lags differ considerably from those obtained by imposing lag shapes. These comparisons show that the ROR to public R&D are sensitive to the lag shape as well as its length and that the omission of other technology variables, such as mechanical and chemical patents pertaining to agriculture and farm size can bias the ROR.