What clone coverage can tell

In research and practice there is a desire to express the amount of cloning in a system in a compact form and compare different systems with each other. A popular choice for doing so is to use the clone coverage - the percentage of source code being part of at least one clone. However, the clone coverage is strongly influenced by the parameters used for clone detection and the peculiarities of each system. In this paper, we summarize certain pitfalls and argue that clone coverage values should be interpreted with care.