I have a question on the information from the biobirth file for the years 2022, 2023 and 2024.
There are several values of the variable “sumkids” that are missing in those years. It seems that the share of respondents with zero children is very low for those years. Is the value missing in case of no kids or what is the reason of this missingness? Is there any other available variable for the children biography of respondents interviewed for the first time in these years?
I would just need information about the first child of respondents (currently I am using kidgeb1 and kidmon01). I did not find an explanation for this, but maybe I missed some relevant documentatio n.
The BIOBIRTH dataset contains information on biological parent–child relationships for all persons who have lived in a SOEP household at any survey wave since 1984. (The population of BIOBIRTH corresponds to the population of PPFAD.)
The variables in BIOBIRTH are generated from two different data sources:
Gross/tracking data (dataset: pbrutto,https://companion.soep.de/Data%20Structure%20of%20SOEPcore/Data%20Sets.html#tracking-data): these data are not reported directly by respondents but are generated in the course of fieldwork. The pbrutto dataset includes all respondents who were either interviewed for the first time or contacted for a re-interview in a given survey wave.
The generated variables biokids, bioyear, and bioage are based on information from the Biography Questionnaire (i.e., the biol dataset). The variable bioyear indicates the survey year in which the respondent completed the Biography Questionnaire (corresponding to the variable syear in the biol dataset).
In contrast, information derived from the tracking data is not associated with a survey year in BIOBIRTH, because information on biological children is considered time-invariant. Therefore, there is no corresponding syear variable for these records.
The variable biokids is generated from the respondents’ answers in the Biography Questionnaire. The determination that a respondent has no biological children (0 children) is made only for these cases. The variable sumkids combines information from both data sources (the Biography Questionnaire and the tracking data) and reports the total number of biological children.
For respondents who completed the Biography Questionnaire in 2022 or later (i.e., bioyear ≥ 2022), cases with 0 biological children were not recorded due to a programming error. As a result, these cases appear as missing in sumkids. This issue will be corrected in the SOEP release (v43).
Please let us know if you have any further questions.