Why is Person.brith_datetime "highly encouraged"?

[MelaniePhilofsky]

Per the CDM conventions, the person.birth_datetime is "highly encouraged". I'm curious, why is it encouraged? This is a nullable field and it is not used in Atlas. If an exact month, day and time is needed for observational research, imputing a time will give false results.

Wording from the ETL section of the person.birth_datetime field: " This field is not required but highly encouraged. For data sources that provide the precise datetime of birth, that value should be stored in this field. If birth_datetime is not provided in the source, use the following logic to infer the date: If day_of_birth is null and month_of_birth is not null then use the first of the month in that year. If month_of_birth is null or if day_of_birth AND month_of_birth are both null and the person has records during their year of birth then use the date of the earliest record, otherwise use the 15th of June of that year. If time of birth is not given use midnight (00:00:0000)."

[clairblacketer]

@MelaniePhilofsky we decided it was "highly encouraged" because it is the only actual birth date field in the CDM. The point here was to say if you have the true birth date, you should put it here and not leave it blank just because it is not required. The time is less important but birth date itself is very useful, especially in many current studies looking at mother-infant linked cohorts.

[MelaniePhilofsky]

Thanks, @clairblacketer for the reasoning. The birthdate can be obtained by combining year_of_birth, month_of_birth, and day_of_birth. My concern is with giving guidance for the imputation of time. If a data source doesn't contain a time for an event, it should be left NULL. The analyst using the data doesn't know time is imputed and not correct.