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Questions about Data

WAVE I

    How many Wave I in-home respondents have in-school questionnaire data?

    15,356 of the Wave I in-home respondents also have in-school data.

     

    What was the response rate for the Wave I school administrator questionnaire?

    A total of 132 schools were included in the Add Health Wave I sample.  An administrator from each school was asked to complete a questionnaire.  The response rate among administrators was 98.5%.

     

    What was the response rate for the Wave I parent questionnaire?

    The parent questionnaire response rate was 85.4% for the child-specific data.

     

    What is the best way to compute age in the Add Health Wave I in-home data?

    To compute a Wave I age variable with the Wave I data, use the following variables and formula:

    IMONTH - Month interview completed
    IDAY - Day interview completed
    IYEAR - Year interview completed
    H1GI1M - What is your birth date? month [and year]
    H1GI1Y - What is your birth date? [month and] year

    The respondent's age is constructed using the interview completion date and date of birth variables. Because only the month and year of birth are available, 15 is used as the day of birth when calculating age. Consult the Introduction to the Adolescent In-Home Codebook to be sure to take into account the respondents whose birth date and/or interview date is incorrect.  Additionally, a few birth dates were corrected during the four waves of data collection so the Wave I date of birth should be compared to the last wave of data for the respondent.  The last wave of participation is considered the most correct.

    SAS programming code that can be used to construct a Wave I AGE variable using Wave I variables is provided below.

    idate=mdy(imonth,iday,iyear);
bdate=mdy(h1gi1m,15,h1gi1y); 
age=int((idate-bdate) / 365.25);

    The code to construct Wave I age in Stata is below.

    recode h1gilm (96=.), gen (w1bmonth)
recode h1gi1y (96=.), gen (w1byear)
gen w1bdate = mdy(w1bmonth, 15,1900+w1byear)
format w1bdate %d
gen w1idate=mdy(imonth, iday,1900+iyear)
format w1idate %d
gen w1age=int((w1idate-w1bdate)/365.25)

    This information is provided by the Add Health team as a service to the Add Health research community. It is provided "as is" with no guarantees as to suitability for a particular purpose.

     

    What does the Wave I variable COMMID represent?

    The COMMID variable groups together the respondents who attend the high school and feeder school that make up the 7 - 12 grade span for the strata.

     

    Why are there 1,821 respondents without a Grand Sample Weight at Wave I?

    The following Wave I cases could not be weighted:
    1. cases added in the field
    2. cases selected as a pair (twins, half-sibs) where both were not interviewed
    3. cases without a sample flag
    4. respondents from schools outside of the 80 strata

     

    WAVE II

    What was the response rate for the Wave II school administrator questionnaire?

    A total of 132 schools were included in the Add Health Wave II sample.  An administrator from each school was asked to complete a questionnaire.  The response rate among administrators was 87.0%.

     

    How do I code gender changes between Wave I and Wave II?

    When there is a discrepancy between the Wave I and Wave II gender of a respondent, use the Wave II gender. The restricted-use data include 23 cases in which the Wave I variable BIO_SEX and the Wave II variable BIO_SEX2do not match. The Wave II data have been confirmed as correct. Wave II includes 7 cases in which the variable SEXFLG2 equals 1. This indicates that the incorrect gender was used to control the questionnaire skips during the interview. The variable BIO_SEX2 was corrected, but answers to questions based on gender will be incorrect.

     

    WAVE III

    Where can I find the monograph about biomarkers collected in Wave III?

    "Biomarkers in Wave III of the Add Health Study" is available in pdf format. The monograph outlines relevant procedures, design, and sampling schemes used in the collection of biomarker data, and serves as a user guide for analysis and interpretation.

     

    How can I obtain a copy of the first release of the Education Data?

    The restricted-use Education Data, collected by the Adolescent Health and Academic Achievement Study, are available through the Add Health contract. For users who already have a contract, email Tannaz Sabet at ICPSR to request an order form for the Education Data. A copy of the public-use version of the file can be downloaded from the ICPSR website.

    When there are gender discrepancies between Wave I and Wave III, how do I know which one is correct?

    There are 20 cases in which Wave III gender (BIO_SEX3) does not match the Wave I gender (BIO_SEX). At Wave III, the preloaded gender variable came from the last wave of available data. Eighteen of these inconsistent cases match the Wave II gender (BIO_SEX2) and were confirmed at Wave III as being correct. Of the remaining two inconsistent cases:

    In one case the Wave III gender, female, was confirmed by the Add Health security manager as being correct.

    In the last case, both the Wave I and Wave II gender are listed as male, which is correct. For this case only, the Wave III gender is incorrect.

     

    When I calculate a Wave III respondent age using the birth date (month, 15, year) and date of interview, I do not get the same age for some respondents as the one found in variable CALCAGE3. Why does this happen?

    The age calculated during the interview uses the actual day of birth, which is not released with the Add Health data. During the Wave III interview, the age of the respondent was calculated by the computer interviewing program and then verified by the respondent. The discrepancy in the ages occurs when a respondent is interviewed during his or her birth month.

     

    How many of the interviewed Wave III public-use sample were originally selected for the core and high education black samples?

    Wave III public-use sample = 4,882

    Core sample only = 4,490

    High education black sample only = 325

    Both samples = 67

     

    WAVE IV

    How many of the interviewed Wave IV public-use sample were originally selected for the core and high education black samples?

    Wave IV public-use sample = 5,114

    Core sample only = 4,699

    High education black sample only = 345

    Both samples = 70