Methods and applications are inextricably linked in science, and in
particular in the domain of text-as-data. In this paper, we examine one such
text-as-data application, an established economic index that measures economic
policy uncertainty from keyword occurrences in news. This index, which is shown
to correlate with firm investment, employment, and excess market returns, has
had substantive impact in both the private sector and academia. Yet, as we
revisit and extend the original authors' annotations and text measurements we
find interesting text-as-data methodological research questions: (1) Are
annotator disagreements a reflection of ambiguity in language? (2) Do
alternative text measurements correlate with one another and with measures of
external predictive validity? We find for this application (1) some annotator
disagreements of economic policy uncertainty can be attributed to ambiguity in
language, and (2) switching measurements from keyword-matching to supervised
machine learning classifiers results in low correlation, a concerning
implication for the validity of the index.

通过分析一个测量经济政策不确定性的经济学指数，探讨了文本 - 数据应用中的研究方法和应用之间的联系，并发现了对文本 - 数据方法论的研究问题。研究结果表明，(1) 作为关于经济政策不确定性的注释者的分歧可以归因于语言的模糊性，(2) 从匹配关键字的方法转向监督式机器学习分类器的方法将导致低相关性，这对指数的有效性有潜在影响。