Econometric Models for Count Data with an Application to the Patents-R&D Relationship
Econometric Models for Count Data with an Application to the Patents-R&D Relationship
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DOI：
10.3386/t0017
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发表时间：
1984-10
期刊：
影响因子：
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通讯作者：
J. Hausman;Bronwyn H Hall;Z. Griliches
中科院分区：
文献类型：
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作者：
J. Hausman;Bronwyn H Hall;Z. Griliches
本文重点是在面板数据的背景下开发和调整计数（非负整数）统计模型，并使用它们来分析专利与 RD 持久个体（固定或随机）效应以及泊松概率函数中的“噪声”或随机性之间的关系。我们将我们的模型应用到 Pakes 和 Griliches 之前通过 1968-74 年七年对 128 家公司的观察来分析的数据集。我们的统计结果清楚地表明，为了使数据合理化，我们需要在条件内维度中进行扰动，并在边缘（之间）维度中进行具有不同方差的不同扰动。添加公司特定变量、日志价值和科学行业虚拟变量，消除了单个公司的专利倾向与其研发强度之间的大部分正相关性。另一个新发现是，专利与研发关系存在交互负面趋势，即企业从最近的研发投资中获得的专利越来越少，这意味着研发的“有效性”或生产力下降。
This paper focuses on developing and adapting statistical models of counts (non-negative integers) in the context of panel data and using them to analyze the relationship between patents and RD persistent individual (fixed or random) effects, and "noise" or randomness in the Poisson probability function. We apply our models to a data set previously analyzed by Pakes and Griliches using observations on 128 firms for seven years, 1968-74. Our statistical results indicate clearly that to rationalize the data, we need both a disturbance in the conditional within dimension and a different one, with a different variance, in the marginal (between) dimension. Adding firm specific variables, log book value and a scientific industry dummy, removes most of the positive correlation between the individual firm propensity to patent and its R&D intensity. The other new finding is that there is an interactive negative trend in the patents - R&D relationship, that is, firms are getting less patents from their more recent R&D investments, implying a decline in the "effectiveness" or productivity of R&D.