In SAS, how can I calculate age from the date-of-birth data?

SAS provides the DATE() and MDY() functions to calculate age. In SAS, date type variables contain the number of days between January 1, 1960, and the date specified. To compute age using a date of birth and the current date, use the following code:

The floor function takes the integer part of age for colloquial usage, but does not take into account the effect of leap years. To avoid this problem, use the intck function by replacing age = floor(days / 365); in the above code with:

age = floor ((intck('month',birthday,today) - (day(today) < day(birthday))) / 12);

The input format MMDDYY6. specifies month, day, and year in six digits. You can also use other formats, such as MMDDYY8. (e.g., 12/31/68, 12-31-68, 12.31.68, or 12311968), DDMMYY6., and DDMMYY8..

DATE() returns the current date set in the computer. To specify a particular day, use the MDY() function as follows:

For more information about accurately calculating age in SAS, see the SAS knowledge base document Accurately Calculating Age with Only One Line of Code.

For more information about statistical and mathematical software, email the UITS Stat/Math Center, visit the center's web page, or phone 812-855-4724 (IUB) or 317-278-4740 (IUPUI). The center is located in Bloomington at 410 N. Park Avenue, and is open for consultation by appointment Monday-Friday 9am-5pm.

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