A suggested framework for classifying the modes of cycle research
指出周期概念在实证研究中很少被精确定义，研究者常使用不同定义。提出基于测量序列和识别方式的双重分类框架，并展示不同类别下周期的存在和性质差异。
Abstract The paper argues that it is important to realize that the concept of a cycle has rarely been precisely articulated in empirical work and that often researchers are using very different definitions of it. We propose a two‐fold classification based upon what series one is measuring a cycle in and how one would recognize a cycle in such a series. The paper illustrates how one can then categorize existing research based upon how it answers these questions. It also shows that the existence and properties of a cycle differ greatly depending upon which of the categories the researcher is using. Copyright © 2005 John Wiley & Sons, Ltd.