using birth date to calculate age?

[bamboo Zhu]

Hi everyone,

I have a question about calculating age.

gen age = (DATE-BIRTH_DATE)/365.25, we usually get the age with decimal.

If age=10 years and 8 months, should we count it as 11 years or 10 years?

Thanks.

[Clyde Schechter]

The problem with "age" is that it is defined differently for different purposes. In normal conversation, if asked how old you are, most Americans will respond with their age at their last birthday. (10 years in the case of your example.) But for insurance underwriting, you are evaluated by your age at your nearest birthday (11 years in this case, but 10 years if the exact age were 10 years and 4 months). In clinical practice, age at last birthday is typically used, although for children in the first few years of life, age is given in months. In most epidemiologic research, when the date of birth is available, age is typically calculated by the formula shown in #1, and it is not rounded off at all but used with the fractional part.

So the answer is that it depends.

[bamboo Zhu]

Thank you very much for your answers, Dr. Schechter.

I used EHR data, and the age is not available. so I want to calculate the patients' age at admission by using birth date and admission date. I need to calculate mean of age and proportions for age groups. I think using age with two decimals seems to not very good, so I want to calculate age without decimals, then move to calculate the mean and proportions.

In my case, I used years without the fractional part (not rounded off), is that a good opinion?

Thank you very very much.

[Bruce Weaver]

Here is a 2014 thread that may be of interest.

• https://www.statalist.org/forums/for...-and-test-date

[Clyde Schechter]

For your purposes I would use the age including the fractional part; I would neither round nor truncate to integers.