Literal question
4. How old are you?
Write the age in years. If under 1 year of age, write 00. If the age is unknown, write "doesn't know."
Years ____
Interviewer instructions
Question 4 How old are you?
Write down the person's age in completed years, in other words, the age of the person on the last birthday. For those less than a year old, write down "00". Use numbers, not letters, to make the annotation.
If there is some doubt in the person when answering the question, try to get the exact age. One resource is the Personal Identity Card.
When a person does not know his/her age, as occasionally happens among persons of advanced age, try to help by making references to historical events or simple local happenings. The age of a person also can be estimated with enough precision, relating the age of a woman when she had a baby to the current age of that child; or how old when getting married or consensually united and remembering how many years that they have been married or consensually united. In these cases, when writing down the estimated age, this age should be followed by the letter "E". Example: 53E; 68E; etc.
If after having exhausted all resources it is not possible to get or estimate the age of the person, write "not known".