6 WHAT FURTHER RESEARCH IS NEEDED? So FAR As IT 1s Now KNOWN, then, we have described the general pattern of public library use in the United States today—the people who use the library and what they use it for. If these are the major generalizations about public library service that emerge from a review of the literature, what are the implications for research? In what areas is further study needed? It is obvious that there are such areas. Time and again in this review the deficiencies and the voids in the research literature have been clearly visible. Time and again conclusions have had to be based upon results that were partial, methodologi- cally suspect, or improperly classified. The disparity between what is available as knowledge about the field and what might reasonably be wanted or expected is considerable. This defi- ciency of research literature is both general and special. Some general deficiencies run through most of the studies in the field. Even in those which are technically satisfactory in other ways, the classification of library materials and library clientele is usually dictated by what is easy and convenient rather than by what is appropriate for the problem at hand. The types of books lent by the public library are usually de- scribed simply by the “adult-juvenile” or “fiction-nonfic- tion” categories, although for many purposes other systems of classification (by content or by quality or by “level”) would be appropriate. And the clients of the public library are de- scribed by the traditional categories of sex, age, education,