The 'Children of twins' (CoT) dataset contains information on the children of the twins interviewed in TwinLife. The information was collected from the twins themselves during the fourth face-to-face interview (F2F4, wid=7) as part of the CAWI interview. This means that the twins, who already have children, answered a series of questions about each of their children. For user-friendly data handling, the variables were converted from wide to long format during data preparation and stored in a separate dataset. Thus, each child of a twin has a unique person number and a separate row with all available information in the child record. The usual variables wid, fid, pid, cgr, ptyp, sex, etc. store information about the person number, sex, cohort, etc. of the responding twin who is the parent of the child. The corresponding information on the children of the twins is stored in the variables cotpid, cotage, cotsex, etc. The variable cotno indicates which child of the twin it is and the letter suffix the child had at the time of the original interview (h, i, j, k, l). The children are listed in order of birth, i.e. the first child is the oldest child of the twin. For documentation purposes, the filter definition only includes the filter expression for the first child (suffix h). However, the filter conditions were applied in a loop for each child, i.e. for the corresponding suffix (h, i, j, k, l). Children who were reported in the family questionnaire in the F2F waves or in the child module (variables cts*) in F2F3, but for whom no information was available in the CoT questionnaire module, were also included in the data set. This may be the case if the twins themselves did not participate in the F2F4 data collection or if the CoT module was not started due to a technical error.
The 'Children of twins' (CoT) dataset contains information on the children of the twins interviewed in TwinLife. The information was collected from the twins themselves during the fourth face-to-face interview (F2F4, wid=7) as part of the CAWI interview. This means that the twins, who already have children, answered a series of questions about each of their children. For user-friendly data handling, the variables were converted from wide to long format during data preparation and stored in a separate dataset. Thus, each child of a twin has a unique person number and a separate row with all available information in the child record. The usual variables wid, fid, pid, cgr, ptyp, sex, etc. store information about the person number, sex, cohort, etc. of the responding twin who is the parent of the child. The corresponding information on the children of the twins is stored in the variables cotpid, cotage, cotsex, etc. The variable cotno indicates which child of the twin it is and the letter suffix the child had at the time of the original interview (h, i, j, k, l). The children are listed in order of birth, i.e. the first child is the oldest child of the twin. For documentation purposes, the filter definition only includes the filter expression for the first child (suffix h). However, the filter conditions were applied in a loop for each child, i.e. for the corresponding suffix (h, i, j, k, l). Children who were reported in the family questionnaire in the F2F waves or in the child module (variables cts*) in F2F3, but for whom no information was available in the CoT questionnaire module, were also included in the data set. This may be the case if the twins themselves did not participate in the F2F4 data collection or if the CoT module was not started due to a technical error.