This report presents the analysis conducted on relating pavement performance or response measures and design considerations to specific pavement layers utilizing data contained in the Long-Term Pavement Performance Program National Information Management System. The goal of this research activity was to enhance implementation and use of the 1993 AASHTO Design Guide through improved materials characterizations. Specifically, the focus of this research activity was to identify the differences that exist between laboratory measured and backcalculated resilient moduli; determine the applicability of the C values, drainage coefficients, and relative damage factors that are included in the Design Guide; and provide procedures to adequately consider the seasonal variation of material properties as related to flexible pavement designs. Based on these results, design pamphlets have been prepared in support of the AASHTO Design Guide. These design pamphlets are documented and included in other reports. The results reported here form the basis and background for those design pamphlets.