Retention

This section provides sample sizes for the number of times younger children and young adults of different ages have been interviewed over the life course of the survey. Given that the child interviewing process began with the 1986 interview round and continued on a biennial basis through 2014 for the Child Supplement and 2016 for the Mother Supplement, the maximum number of child interviews a respondent could have is eight, since children age into the Young Adult survey the survey round in which they turn 15 or older (12 or older since 2016) and the Young Adult interviews began in 1994. Clearly, the content varies considerably between the Child and Young Adult interviews, partly because in most rounds only younger children were assessed, and partly because many of the questions are life-cycle specific. Many questions that might be relevant for an eight- or a fourteen-year old might not be appropriate for an older adolescent, much less someone in their twenties, thirties, or forties. Additionally, there have been some changes in questions and question wording over time, so researchers who are using these data in a longitudinal manner need to carefully review the content of the questions they are using.

The Child and Young Adult surveys are characterized by inherently different question structures, modes of data collection, and indeed potentially different research agendas. It is therefore useful to present separately the sample sizes for younger and older children, even though the ultimate research agenda in many instances may join these two sample types.

• The Number of Child Interviews
• The Number of Young Adult Interviews

The Number of Child Interviews

Table 1 presents the number of child interviews ever completed by the NLSY79 children as of the most recent survey round. This table references age at the end of the survey year (December 31) rather than the survey date because the age determination for inclusion as a young adult rather than a younger child was the age as of the end of the calendar year. This method of computing age avoids a need to split the fourteen-year old age group between a younger child and a young adult component. Whether one uses a survey date or end-of-year age typically has little impact on the magnitude of age-specific sample sizes. Most estimates of sample size for younger children in this users guide use child age as of the survey date. This is the reason why sample sizes by age presented across tables may not always be identical.

Table 1 indicates the total number of child interviews reported for each NLSY79 child who has ever been interviewed, regardless of current age. For this table, a child is defined as interviewed if the sampling weight (CSAMWTyyyy or CSAMWT_REVyyyy) is greater than zero for a given survey year. The greatest number of possible child interviews would be eight biennial interviews. Only 727 of the respondents at the end of 2020 fall into that category. However, Table 1 shows much larger numbers of children in all the other interview frequency categories. Children who fall into the older age categories as of the current round, but who have completed only a small number of interviews (e.g., 11 year olds with only one or two interview points), have missed some interviews. For example, an 11 year old could potentially have six completed interviews. The implications of repeat interviewing for these younger children are expanded on in the documentation on the child assessment data, where the extent of interview repetition is connected with the specific cognitive and socio-emotional assessments that the children complete at various ages.

The Number of Young Adult Interviews

Table 2 extends this interview repetition concept to the young adult component of the survey. Since the young adult interview has been ongoing only since 1994, the maximum number of young adult interviews possible by 2020 is fourteen. It should be recalled that young adults age 21 or over at the date of the 1998 interview were not interviewed in that year. This leads to a potential four-year interview gap, between 1996 and 2000, for these cases. Similarly, those who were not fielded in 2000, as part of the children aged 0 to 20 of 38% of minority oversample mothers not eligible in that round, have a four-year gap from 1998 to 2002 and will have missed either their last child round or a young adult round. From 2002 to 2008, the young adult sample includes all youth age 15 and over who were available to be interviewed. Beginning in 2010, Young Adult respondents over the age of 30 will be interviewed every four years. The interviewed sample is selected by age as of December 31 of the survey year, so that approximately half of the older young adults are eligible each round. Since 2010, young adults age 31-32, 35-36, 39-40, 43-44, etc. as of December 31 of the survey year have not been fielded. In Table 2, while the age references the end of 2020, a particular young adult may not have been interviewed in that year. Of the 8673 young adults included in Table 2, 5670 were fielded and 4354 were interviewed in 2020. Table 2 also shows that there are substantial numbers of young adults who have had at least nine young adult interview points and a large number who have had eight interviews as young adults since 1994. Among young adults who have completed eight or more young adult interviews, more than 77% have completed every interview for which they were  eligible.

Young Adult Assessment History. As can be seen in Table 2, most of the young adults have had a number of child assessment points prior to reaching age 15 and then, depending on their current age, between one and eleven Young Adult interviews since that date. The nature of the data collection changes in fundamental ways when a child transitions to being a young adult. Prior to 2016, children under age 15 were administered (or their mother completed) a variety of assessments. For children in this age range, the mother also provided a variety of information about the child's health, education, and selected other items. Beginning with the 1988 survey, children age ten and over self-administered a set of questions about their own behaviors and attitudes in a variety of domains, including education, family and peer interaction, normative and non-normative attitudes and behaviors. In 2016, no children were directly assessed, and mothers completed Mother Supplements for children ages 0 to 13. In 2018, only a small number of child health and schooling questions were asked of the mothers.

Starting in 1994, once the children reached 15, they completed the Young Adult interview designed to address most of the major dimensions of their lives: schooling, employment, family, peer interactions and issues of sexuality, and other behaviors and attitudes that permit researchers to examine in context the experiences of these young adults in a holistic manner. Beginning in 2016, children ages 12 and up were included in the YA fielding, although the children age 12 and 13 answered significantly fewer questions than those 14 and older. A flow diagram that would cross the possible survey points, encompassing the period from 1986 to the present, would follow a child from preadolescent years, describing the child development process in some detail, parallel family and child behaviors and attitudes, and culminate in a detailed profile of later adolescent-early adult transitions to adulthood. Table 1 and Table 2 are designed to clarify the size of the sample that permits one to maximize the panel dimensions of the data set.