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Linking NLSY79 Mothers and Their Children

Tutorial objective and prerequisites

Objective

The goal is to link NLSY79 mothers with their children. This tutorial explains the general logic to link mothers and children of any age covered in the Children of the NLSY79. The tutorial then gives a specific example of using data on mothers and young adult daughters by creating two variables: (1) whether the mother had a first birth prior to age 18, and (2) whether the daughter had a first birth prior to age 18. This allows one to examine intergenerational correlations in teenage childbearing.

Knowledge assumed

This tutorial assumes that you already know how to use the NLS Investigator to create a tagset that saves your variables and to extract data. If you need assistance with the NLS Investigator before starting this tutorial, please review the Investigator User Guide or contact NLS User Services.

Background reading

To understand how to link mother and child/young adult files, see the NLSY79 Child and Young Adult Users Guide section on Linking Children, Young Adults and Mothers and Appendix E and Appendix F for sample SPSS and SAS programs. In the NLSY79 User's Guide, see the sections on Age and Fertility.

Example: Intergenerational linking of NLSY79 mothers and their young adult daughters

Preview of steps

  1. Step 1: Find and extract the Child/Young Adult variables
  2. Step 2: Find and extract the NLSY79 variables
  3. Step 3: Merge NLSY79 and Child/Young Adult data files and create new fertility variables

Additional information provides the statistics output from the sample program and suggestions for extending the tutorial.

Step 1: Find and extract the Child/Young Adult variables

Find and extract the respondent IDs, age at first birth, and other needed variables in the Child/Young Adult data set using the NLS Investigator.

  1. Start by finding the mother and child/young adult IDs.
    • Select variables by reference number and pick "C000" and then submit. C00001.00 is the respondent ID from the child/young adult file, and C00002.00 is the mother ID. Tag these two variables.
    • Note that the respondent ID, C00001.00, is a comprehensive ID variable, created for all children regardless of age or young adult status.
    • For this example, one could also use the Young Adult ID, Y00001.00, which will have the same value as C00001.00, but exists only for those children who participate at age 15 or older.
  2. Find age at first birth.
    • Search on the YA Fertility and Relationship Data/Created Area of Interest and Survey Year = 2006 (or whatever the most recent survey year is). Y12111.00 is age at first birth at the most recent interview the young adult completed. Tag Y12111.00.
  3. Find the sex variable, since this tutorial looks at young adult females, and find whether the respondent was at least 18 years old at her last young adult interview.
    • Select variables by the YA Common Key Variables Area of Interest.
    • Scroll down and select sex (Y06774.00), most recent young adult interview year (Y12051.00), and age at each young adult interview (Y19485.00, Y16727.00, Y14343.00, Y11924.00, Y09748.00, Y06776.00, Y03424.00).
  4. Run an extract to create the data set and corresponding SAS/SPSS/STATA/R program.

Using the NLS Investigator

To create a tagset of specific variables and then extract the data set, use the Save / Download Tab in the NLS Investigator.

Step 2: Find and extract the NLSY79 variables

Find and extract comparable variables (to those in Step 1) in the NLSY79 data set using the NLS Investigator.

  1. Start by finding the NLSY79 respondent ID.
    • Select variables by reference number and pick "R000" and then submit. R00001.00 is the respondent ID for the mother. Tag this variable.
    • Note that R00001.00 = C00002.00 in the child/young adult data set.
  2. Search on the Word in Title Birth, Search Variable Title Age, and the Fertility and Relationship History/Created Area of Interest.
    • From the fairly long list, you can find the age at first birth created variables from 1982 forward (R08988.40, R11468.32, R15220.39, R18927.39, R22598.39, R24480.39, R28778.00, R30768.44, R34079.00, R36590.49, R40094.49, R44449.00, R50877.00, R51730.00, R64866.00, R70144.00, R77120.00, R85045.00, T09962.00).
    • Note that you will need this variable for each year because if the respondent misses an interview, it is not created for that interview year.
  3. Searching on Word in Title Age and the Key Variables Area of Interest will provide a list of created variables for age at the interview date, which you need from 1982 forward (R08983.10, R11451.10, R15203.10 R18910.10, R22581.10, R24455.10, R28713.00, R30750.00, R34017.00, R36571.00, R40076.00, R44187.00, R50817.00, R51670.00, R64798.00, R70075.00, R77048.00, R84972.00, T09890.00).
  4. Run an extract to create the data set and corresponding SAS/SPSS/STATA/R program (see "Using the NLS Investigator" in Step 1).

Step 3: Merge NLSY79 and Child/Young Adult data files and create new fertility variables

Once you have the two data sets from Steps 1 and 2, you are ready to merge them and start programming the variables. The logic is as follows:

  1. Start by merging the two data sets. Merge NLSY79 mother characteristics in with the Child/Young Adult data set using the code sample below.
  2. Code whether the mother had a birth prior to age 18.
    • Create this variable only for mothers who are interviewed after they turned 18.
    • Calculate the age at last interview and the year of last interview from 1982 forward.
    • Use this information to code the teen birth variable.
  3. Follow similar steps for the young adults.
    • Restrict the data to female young adults, and construct variables for age and year of last interview.
    • Code the teen birth variable for young adults who are interviewed after they turn 18.

Additional information

Final statistics from sample program (data through 2006 survey)

m_teenbirth (mean = .249, N = 3147);
y_teenbirth (mean = .137, N = 2419) smaller sample size because only created for those at least 18;
y_year_lint (mean = 2006, N = 3147)
y_age_lint (mean = 21.3, N = 3147)
m_year_lint (mean = 2005, N = 3147)
m_age_lint (mean = 44.6, N = 3147)

Extensions

This tutorial focuses on linking mothers and their young adult daughters. Similar techniques can be used to link other characteristics of mothers with characteristics of their children. For further suggestions, review the Possible Research Agendas for Intercohort and Cross Generational Research section.