18. Date of birth
Now you are able to record the household members and visitors on the questionnaire, and complete the answers to questions 14-18 and 19-20 for each person.
Question 18: Date of birth or age
The age of an individual is the number of years since birth. It is obtained accurately by difference of date: date of observation (day, month, year) - date of birth (day, month, year). The age of an individual is a very important variable in the sociodemographic and economic analysis of the census data.
Therefore, you must make every effort to obtain this vital information with as much accuracy as possible. Ideally, the birth date of an individual should be expressed in day/month/year format. Try to get maximum accuracy (day, month, year) whenever possible. Check the civil status documents of respondents who have them.
In order to record the response obtained, a distinction must be made among several possible scenarios:
1 - The date of birth information is complete (day, month, year).
2 - The date information is not complete: We know either the month and year of birth, or the year of birth only.
3 - Date of birth information is not available, despite your best efforts; in this case, you must ask the following question: "What is your age?" Always test the plausibility of the answer provided, using simple cues such as: identification of people of the same generation whose age is relatively well known, important historical facts, etc. The answer obtained is transcribed as follows for an age of 42: 42 (age)
Note: For any person born before 1901, even if the date of birth is known, you should not record such a date of birth in the corresponding coding grid on the questionnaire. Instead, in these cases, simply write "97" in the coding grid under the "age" category.