During the last two decades, libraries have shown a considerable degree of momentum in the collection building and readership program activities, involving considerable expenditure of funds. This rapid development of libraries has, as a consequence, generated several evaluative studies on the usefulness of libraries to society. In such evaluative studies, librarians tried to apply (to many extent) several techniques of other fields (such as, mathematics, statistics, operations research, management science etc.) in order to minimize the subjectivity. In particular, quantitative methods, especially the statistical techniques have become popular in recent years for evaluating the effectiveness and efficiency of information services offered by librarians. With an objective to explain statistical methods as they are applied to library and information science, the discussion in the text is application oriented. The book will be most useful to post graduate students of Library and Information Science, teachers and also to practising librarians and information scientists. The book can be treated both as a textbook and source book.