Year 2000

The Year 2000 problem dates back to the 1960's and 1970's when computer memory and storage were both scarce and expensive. To save bits (storage space), early programmers decided to designate years with two digits (e.g., '91) rather than four (e.g., 1991). At the time, few programmers imagined that the systems they built would still be used in the year 2000. Computers understand time numerically - larger numbers mean the future; smaller numbers, the past. The two-digit system sees 1999 as the future, 1997 as the past. Come 2000, though, this system breaks. If a computer says that New Year's Eve is 991231 and New Year's Day is 000101, time will have moved backward since the year '00' is interpreted as 1900. One day in the future becomes 100 years in the past.

The Corporate Personnel System stores all dates with a two digit year. Problems arise only when these dates are compared to other dates. For example, age is computed by subtracting Date of Birth from today's date and dividing by 10,000. So someone born on May 1, 1948 would be age 50 on May 1, 1998 (980501-480501 divided by 10,000 = 50). However, computing this same person's age on May 1, 2000 (000501-480501 divided by 10,000) will not correctly compute to age 52 as it should. For Year 2000 dates to compare properly, either the date fields would need to be expanded to four digit years, or a work-around would have to be put into place.

Due to size limitations of CPS input files from campus payroll systems, it was decided that date fields would not be expanded to four digit years in CPS. We have instead defined three new fields for each date field in CPS effective with March 1998 data. For example, the original Date of Birth (BDATE) field is normally expressed as YY/MM/DD (50/05/05 for an employee who was born on May 5, 1950). The new TBDATE field provides a four digit year expressed as YYYYMMDD (19500505 for an employee born on May 5, 1950). The new T1BDATE field also provides a four digit year but is expressed as YYYY/MM/DD (1950/05/05 for the employee born on May 5, 1950). The new T2BDATE field provides a four digit year in yet a third format, expressed as MM/DD/YYYY (05/05/1950).

Adding a "T" to the beginning of any existing date field's focus name will provide you with a YYYYMMDD format. Adding "T1" to the beginning of any existing date field's focus name will provide you with a YYYY/MM/DD format. And adding "T2" to the beginning of any existing date field's focus name will provide you with a MM/DD/YYYY format.

Last updated June 4, 1998