Codes and Frequencies
For sample children age 4 to 17, STOMACHE reports parents' responses to a question about whether, during the past 6 months, the child often complained of headaches, stomachaches, or sickness.
The interviewer began this part of the survey by stating, "I am going to read a list of items that describe children. For each item, please tell me if it has been not true, somewhat true, [or] certainly true for [sample child] during the past 6 months," and handed the respondent a flashcard listing the three acceptable responses.
STOMACHE was part of the Strengths and Difficulties Questionnaire Extended (SDQ-EX), which, according to the 2001 and 2003-2004 Manuals, was included "to monitor emotional and behavioral problems in children and the impact that these problems have on children's lives."
The Field Representative's Manuals for 2001 and 2003-2004 directed interviewers that, when an item included two or more behaviors linked by an "or":
The Manuals for 2001 and 2003-2004 directed that the interviewer "should emphasize the word COMPLAINS. We are not interested in how often the child is sick, but only in whether the child complains a lot, regardless of whether or not they are sick." As discussed in more detail in below, STOMACHE is intended to be a measure of the child's "emotional symptoms," rather than a measure of physical illness.
The Manuals for 2001 and 2003-2004 also provided directions on how interviewers should respond if parents indicated that the child was taking medication:
Strengths and Difficulties Questionnaire Extended
STOMACHE is part of a set of 33 questions from the Strengths and Difficulties Questionnaire Extended (SDQ-EX) developed by Dr. Robert Goodman, Institute of Psychiatry, London, England.
As the Appendix on SDQ in the 2001 and 2003-2004 Codebook of the NHIS public use files explains:
- emotional symptoms;
- conduct problems;
- hyperactive behavior;
- peer relationships;
- prosocial behavior.
The survey forms for 2001 and 2003-2004 also acknowledged the debt to Dr. Goodman, as follows:
This information was included for legal reasons and was not shared with survey respondents. More information on the SDQ is available at www.sdqinfo.org.
As noted in the Appendix on SDQ in the 2001 and 2003-2004 Codebook, STOMACHE is an element of the 5-item subscale dealing with emotional symptoms.
The other elements of this subscale are:
- Often seems worried, past 6 months (WORRIED)
- Often unhappy, depressed, or tearful, past 6 months (UNHAPPY)
- Nervous or clingy in new situations, past 6 months (CLINGY)
- Many fears or easily scared, past 6 months (FEARFUL)
Valid responses for these questions were "not true," "somewhat true," and "certainly true." A response of "not true" for these variables (code 0 in IPUMS NHIS) implies the lowest level of emotional symptoms; a response of "certainly true" for these variables (code 2 in IPUMS NHIS) implies the highest level of emotional symptoms; and a response of "somewhat true" for these variables (code 1 in IPUMS NHIS) implies an intermediate level of emotional symptoms. Researchers may choose to use a single variable from this set, but they can also sum the scores across the 5 variables. Summing these elements yields a total score for emotional symptoms ranging from 0 (the lowest level) to 10 (the highest level).
Summing the values for these variables yields valid totals only if the analyst excludes not in universe cases (persons other than sample children age 4-17, code 6 in IPUMS NHIS) and cases with missing information (codes 7, 8, and 9 in IPUMS NHIS).
The SDQ Scoring Guide provides guidelines for interpreting subscale scores (with Not in Universe and unknown cases excluded) for the SDQ-EX. For "Parent Completed" results (as in the NHIS), the guide suggests a three-band or four-band approach for interpreting the summed score for "Emotional Problems." Under the original three-band categorization, the summed Emotional Problems score can be identified as normal, borderline, or abnormal: a score of 0-3 is normal; a score of 4 is borderline; and a score of 5-10 is abnormal. Under the newer four-band categorization, the summed score can be identified as close to average, slightly raised, high, or very high: a score of 0-3 is close to average; a score of 4 is slightly raised; a score of 5-6 is high; and a score of 7-10 is very high.
The SDQ includes 5 subscales for measuring different aspects of child mental health. The five subscales (i.e., emotional symptoms, conduct problems, hyperactivity behavior, peer relationships, and prosocial behavior) can be scored separately to look at specific psychological characteristics (as described above, for the "emotional symptoms" subscale). Alternatively, items in four of the five subscales (emotional symptoms, conduct problems, hyperactivity behavior, and peer relationships) can be added for an overall score from 0 to 40.
Variables from the SDQ receive codes in IPUMS NHIS that facilitate this scoring process. More specifically, the response that corresponds to the lowest likelihood of a psychological problem is coded as 0 in IPUMS NHIS; the response that corresponds to the highest likelihood of a psychological problem is coded 2 in IPUMS NHIS; and the response that corresponds to an intermediate level likelihood of a psychological problem is coded 1 in IPUMS NHIS.
This coding strategy to facilitate scoring means that a given parental response of "not true" or "certainly true" may be sometimes coded as 0 and sometimes coded as 2. (Responses of "somewhat true" are always coded 1.) For example, the question, "During the past 6 months, has [child] often complained of headaches, stomach aches, or sickness?" presupposes that "not true" (coded 0 in IPUMS NHIS) implies less emotional symptomology than a response of "certainly true" (coded 2 in IPUMS NHIS). However, with the question, "During the past 6 months, has [child had] at least one good friend?," a response of "not true" implies poorer peer relationships than a response of "certainly true." In the latter case (for the variable HASFRIEND), responses of "not true" are coded 2 in IPUMS NHIS and responses of "certainly true" are coded 0 in IPUMS NHIS.
Once analysts exclude not in universe cases (persons who are not sample children age 4-17, IPUMS NHIS code 6) and cases with missing information (IPUMS NHIS codes 7, 8, and 9), they may sum the values for the following SDQ-EX variables for an overall score of 0 (least likely to have psychological problems) to 40 (most likely to have psychological problems). In addition to the 5 variables (including STOMACHE) used to measure "Emotional Symptoms," as described in the previous section, the variables whose values may summed are:
- Often loses temper, past 6 months (BADTEMPER)
- Generally well behaved, past 6 months (WELLBEHAVED)
- Often fights or bullies kids, past 6 months (BULLIES)
- Often lies or cheats, past 6 months (LIECHEAT)
- Steals from home, school, or elsewhere, past 6 months (STEALS)
- Restless or overactive, past 6 months (OVERACTIVE)
- Constantly fidgeting, past 6 months (FIDGETY)
- Easily distracted, past 6 months (DISTRACTED)
- Thinks before acting, past 6 months (THINKSFIRST)
- Good attention span and finishes tasks, past 6 months (GOODATTEN)
- Prefers to be alone, past 6 months (SOLITARY)
- Had at least 1 good friend, past 6 months (HASFRIEND)
- Liked by other kids, past 6 months (KIDSLIKE)
- Was picked on or bullied, past 6 months (PICKEDON)
- Gets along better with adults than kids, past 6 months (GETALONGAD)
With the exception of the NHIS questionnaire redesign introduced in 2019, STOMACHE is completely comparable over time. This variable is an element of the extended version of the Strengths and Difficulties Questionnaire (SDQ-EX), which was fielded for sample children in the NHIS in 2001, 2003, 2004, and 2019 forward. It is not an element of the abbreviated version of SDQ, which was fielded for sample children in 2002, 2005-2007, and 2010-2018.
From 1997-2000, the NHIS used questions from the Child Behavioral Checklist (CBCL) developed by Dr. Thomas Achenbach to measure children's emotional and behavioral problems. For 2001 forward, the NHIS retained the CBCL questions for children age 2-3, but replaced the CBCL survey with the Strengths and Difficulties Questionnaire (SDQ) for older children.
For the most part, the public use files of the NHIS data include only summary recodes for the CBCL questions, calculated separately for male and female children age 2-3 (MTODMHI, FTODMHI), for male and female children age 4-11 (MKIDMHI, FKIDMHI), and for male and female children age 12 to 17 (MTEENMHI, FTEENMHI). The one exception to this generalization is that variables from the CBCL relating to whether the child had been unhappy or depressed in recent months (TODDEPRES, KIDDEPRES, TEENDEPRES) appear in the NHIS public files.
The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 2001: Sample children age 4 to 17.
- 2003-2004: Sample children age 4 to 17.
- 2019: Sample children age 4 to 17.
- 2001, 2003-2004, 2019
- 2001, 2003-2004, 2019 : SAMPWEIGHT