As a means of studying the present public catalogs and possible catalog format alternatives at the Iowa State University library, a 6-week queuing study was conducted. Objectives of the study were (1) to determine the correlation between other library statistics (e.g., door counts and circulation records) and use of the public catalogs; (2) to calculate the ratio between use of the card catalog and the separate serials catalog; (3) to compare the library staff's use of the catalog with use by the public; and (4) to obtain information about use of the card catalog and the serials catalog in each of several autonomous library service points. The catalogs were observed in 234 10-minute periods. Numerical data gathered from observations are presented in the form of scatter diagrams and histograms comparing card catalog use, circulation counts, and exit counts. The results indicate little correlation between numbers of card catalog users and other staff-gathered user statistics. It was also found that card catalog users arrive randomly, and neither their numbers nor their arrival patterns can be predicted through use of other library statistics. (SW)