| Collection evaluation is a necessary process if libraries want to be effective. The citation checking technique is one of many methods utilized to evaluate collections. This study was undertaken in order to (1) determine whether different indicators of strength of a collection will be obtained when different types of materials (i.e., monographs, periodicals, and dissertations) are used as sources of citations to be compared with a collection; and (2) determine the reliability of these sources.; Three separate samples of citations were randomly selected from 34 monographs, 17 periodical titles, and 31 dissertations on the field of soil science. Each sample of citations was checked against the University of Illinois library system. The results of the matching process were tabulated by type of material, period of publication, and language. The data revealed that the library owns a higher percentage of the items derived from dissertations (91%), followed by the items derived from periodical titles, (87%), and finally, from the items derived from monographs (77%). The application of the chi-square test for equality of proportions to the actual results revealed that these differences are statistically significant. It was also found that the greater diversity of the references drawn from monographs creates variability in estimates of the coverage of the collection when different samples of citations are drawn. |
