The ongoing Consumer Expenditure Survey (CES) provides a continuous flow of information on the buying habits of American consumers and also furnishes data to support periodic revisions of the Consumer Price Index. The survey consists of two separate components: (1) a quarterly Interview Survey in which each consumer unit in the sample is interviewed every three months over a 15-month period, and (2) a Diary Survey completed by the sample consumer units for two consecutive one-week periods. The Interview Survey was designed to collect data on major items of expense, household characteristics, and income. The expenditures covered by the survey are those that respondents can recall fairly accurately for three months or longer. In general, these expenditures include relatively large purchases, such as those for property, or expenditures that occur on a fairly regular basis, such as rent, utilities, or insurance premiums. Excluded are nonprescription drugs, household supplies, and personal care items. Including global estimates on spending for food, it is estimated that about 90 to 95 percent of expenditures are covered in the Interview Survey. The Detailed Expenditure Files were created from all the major expenditure sections of the Interview Survey questionnaires and contain the most detailed expenditure data from the Interview Survey.