In the empirical literature, the analysis of aggregate productivity dynamics using firm-level productivity has mostly been based on changes in the mean of log-productivity. This paper shows that there can be substantial quantitative and qualitative differences in the results relative to when the analysis is based on changes in the mean of productivity, and discusses the circumstances under which such differences are likely to happen. We use firm-level data for Portugal for the period 2006–2015 to illustrate the point. When the mean of productivity is used, we estimate that TFP and labor productivity for the whole economy increased by 17.7 percent and 5.2 percent, respectively, over this period. But, when the mean of log-productivity is used, these two productivity measures decline by 4.3 percent and 1.8 percent, respectively. Similarly disparate results are obtained for productivity decompositions regarding the contributions for productivity growth of surviving, entering and exiting firms.

在经验文献中，使用公司级生产率对总生产率动态进行分析的主要依据是对数生产率平均值的变化。本文表明，相对于基于生产率平均值变化进行分析的结果，结果可能存在实质性的数量和质量差异，并讨论了可能发生这种差异的情况。我们使用葡萄牙在2006-2015年期间的企业级数据来说明这一点。当使用生产率的平均值时，我们估计在此期间，整个经济的全要素生产率和劳动生产率分别增长了17.7％和5.2％。但是，当使用对数生产率的平均值时，这两个生产率度量分别下降了4.3％和1.8％。