In November 1987, the Federal Judicial Center commenced its third major "time study" in the U.S. district courts. Like studies conducted in 1969 and 1979, the purpose of the new study is to develop case "weights" for district court civil and criminal cases.Case weights reflect the difference in average judge time demanded by different types of cases (antitrust cases, for example, have a much higher weight than automobile personal injury cases). Totaling the weights assigned to all cases filed in a district in a particular year yields a measure of the total judicial workload in that district, the district's "weighted filings." Compared to a simple count of the number of cases filed, the weighted filing index is a superior statistical indicator of the burden imposed by a district's caseload.