摘要:Improving on ideas developed in Brief Tests of Collection Strength, this paper presents coverage power tests, an empirical method for evaluating collections in all types of libraries by means of ranked holdings counts from OCLC's WorldCat. The new method measures library coverage of subject literatures across levels of the WLN or RLG collection intensity scales that are increasingly difficult to attain. It defines literatures and collections unambiguously, permits objective comparisons of libraries, and is potentially automatable. Results of 38 tests in nine subjects at 30 libraries have high face validity in rating collections. Graphical analysis with the new method also clarifies the bibliometric relation between individual collections and subject literatures.