Volumes 1-4 of the GSLP Loan Estimation Model present the historical and legislative background of the Guaranteed Student Loan Program, give an analysis of the data base used to develop the GSLP Loan Estimation Model, and discuss the development and operation of the model. Volume 1 provides a brief description of the legislative authority for the program and gives a brief description of its operational processes. Volume 2 contains summary statistics and cross-tabulations of loan, borrower, lender, and educational characteristics of GSLP loans. From these comparisons, it is possible to determine Guaranteed Loan participation by age, sex, race, gross and adjusted family income, and type of educational institution attended. Volume 3 provides statistics on borrower, lender, and educational institutional characteristics of default claims under Federal, State, and private nonprofit guarantee agency programs. Comparison of data in Volumes 2 and 3 allows direct answers to the question, "For any particular variable, what percentage of borrowers took loans and what percentage defaulted on these loans?" Volume 4 presents both a general and a technical mathematical discussion of the GSLP L an Estimation Model. The model is divided into two parts: a Loan Flow Model and a Simplex Model. (Author/PC)