The earliest studies sought to show that disparities resulted from the individual characteristics of the judges. A more recent line of investigation emphasizes some aspect of the case, usually extralegal factors associated with the defendant such as race or the geographic area in which the case was decided. Methods used to investigate sentencing disparity have ranged from crude comparisons of small samples of individual cases to sophisticated statistical techniques with large samples, but most results have been unconvincing because of methodological weaknesses. Major problems have been showing that courts are sentencing roughly comparable cases when disparities are uncovered and coding all relevant variables that decisionmakers consider when imposing sanctions. The late 19th century correctional reform movement with its emphasis on rehabilitation legitimized the vast discretion accorded trial court judges and parole boards. Critics have attached this individualized sentencing model in the last decade, advocating a return to the justice model where punishment is proportionate to the seriousness of the offense. In this view, determinate sentencing is achieved by abolishing parole boards and returning term setting to the courts or giving judges sentencing guidelines with a narrow set of durational ranges. Aside from philosophical principles, the more pragmatic reason for promoting uniformity in sentencing is to reduce prison unrest, a theme that has persisted throughout correctional literature since the 19th century. Major barriers to strong and convincing research are the inabilities to conceptualize the norm or standard from which disparity is measured and to define disparity clearly. Objections that a sentence is excessive are often based on subjective evaluations, while a contrasting approach may rely solely on comparisons with a large statistical sample. A review of definitions found in the literature shows that any analysis of disparity must address the characteristics of the sanctions imposed, the details of the offense, and the offender's attributes. The article contains 12 case citations and approximately 55 references. See NCJ-87442.