All dates are represented as daily dates for consistency and ease of use. FRED uses a single date format widely supported by various spreadsheet applications (Excel, Lotus, etc.) and statistical software packages (SAS, Eviews, Stata, RATS, etc.). Because annual, quarterly, and monthly data series may begin at different times during the period (beginning of period, middle of period, etc.), frequencies are converted to the first day of the period for consistency and ease of use. Dates for weekly and daily data series are natively daily dates and not converted. Dates are formatted as YYYY-MM-DD. For example, April 25, 2002, is written as 2002-04-25.
• Annual data: Data for 2004 are represented by the single date 2004-01-01, the first day of 2004.
• Quarterly data: Data for the second quarter of 2005, for example, are represented by the single date 2005-04-01, the first day of the first month of the second quarter of 2005 (the first day of the second quarter of 2005).
• Monthly data: Data for July 2005 are represented by the single date 2005-07-01, the first day of the seventh month of 2005.