The EMODIFF question was asked following a series of either 25 questions (for 2001 and 2003-2004, and 2019 forward) or 5 questions (for 2002, 2005-2007, and 2010-2018) designed to measure the child's difficulties in topic areas covering emotional symptoms, hyperactive behavior, conduct problems, and peer relationships. For these prior questions, the reference period was explicitly defined as the past 6 months. While the question wording for EMODIFF did not specify a time period, the Field Representative's Manuals for 2001 and 2003 forward stated, "If parents ask for the time period for this question, tell them it is also for the past six months." For 2010, in addition to EMODIFF, there is a separate question about children's mental health that specifically asks a yes or no question about whether the sample child had difficulties with emotions, concentration, behavior, or getting along with others during the past 6 months (EMODIFFYN).

As discussed in more detail below, EMODIFF 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." More specifically, in these years, EMODIFF began a section of the SDQ-EX which the NHIS Survey Descriptions describe as "extended questions that provide information on the duration of a child's problem and the impact that problem has on the child and his/her family."

EMODIFF was also one of the six items comprising the brief version of the Strengths and Difficulties Questionnaire, which was included in the NHIS in 2002, 2005-2007, and 2010-2018. The purpose of the brief questionnaire was the same as for the extended questionnaire: "to monitor emotional and behavioral problems in children and the impact that these problems have on children's lives."

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.

EMODIFF was an element in the second part of the SDQ, which the same source describes as follows:

More information on the SDQ-EX is available at www.sdqinfo.org. This source describes the section of the SDQ-EX beginning with EMODIFF as the "Impact Supplement."

These follow-up questions were the basis of the following variables:

• Difficulties upset or distress child (DIFUPSET)

• Child's difficulties interfere with home life (DIFHOME)

• Child's difficulties interfere with friendships (DIFFRIEND)

• Child's difficulties interfere with classroom learning (DIFLEARN)

• Child's difficulties interfere with leisure activities (DIFLEISURE)

The Scoring Guide at the www.sdqinfo.org website provides guidance on how responses for these five variables "can be summed to generate an impact score that ranges from 0 to 10 for the parent-completed version." Under these guidelines, the responses "not at all" and "a little" are given a score of 0; a response of "a medium amount" is given a score of 1; and a response of "a great deal" is given a score of 2. For each of these variables, a score of 0 implies the least impact from the child's difficulty, and a score of 2 implies the greatest impact from the child's difficulty. If the scores for these five variables are summed, the total ranges from 0 to 10, with 0 implying the least impact from the child's difficulties and 10 implying the greatest impact from the child's difficulties.

If parents responded "no" to the opening question about whether the child had difficulties with emotions, concentration, behavior, or getting along with others (EMODIFF), none of these five questions were asked. In such cases, when parents "are not asked to complete the questions on resultant distress or impairment," the Scoring Guide states, "the impact score is automatically scored zero." The same is true when parents reported difficulty in these areas that lasted less than 1 month (and thereby avoided these follow-up questions on "resultant distress or impairment").

The five variables that can be summed to create a total "impact score" receive codes in IPUMS NHIS that facilitate this scoring process. Responses that should receive a score of 0 in the scoring process--namely, "not at all" or "a little"--receive a code of 0 in the first digit. In addition, sample children with no reported difficulties (in EMODIFF) or with no difficulties lasting one month or longer (in DIFMOS) also receive a code of 0 in the first digit in these five variables. (The three different categories, "No difficulty for greater than or equal to 1 month," "not at all," and "a little" can still be distinguished from each other by the respective values of 0, 1, and 2 in the second digit.) The response "a medium amount," which should receive a score of 1, receives a code of 1 in the first digit (and a code of 0 in the second digit). The response "a great deal," which should receive a score of 2, receives a code of 2 in the first digit (and a code of 0 in the second digit). Cases which should be excluded from this summing of scores--that is, not in universe cases consisting of persons other than sample children age 4-17, and cases with a response of "unknown"--all receive a code of 9 in the first digit (with the second digit distinguishing between those not in the variable universe and unknowns.)

Put succinctly, to calculate an "impact score" for the child's difficulties, researchers should 1) exclude cases beginning with a code of 9; 2) group together other categories that share a common first digit; 3) sum the scores across the five variables, using only the first digit of the codes for each variable. The result will range from 0 to 10.

The Scoring Guide at www.sdqinfo.org provides the following guideline for interpreting these results:

Some researchers may prefer to use only some of the "impact" variables (DIFUPSET, DIFHOME, DIFFRIEND, DIFLEARN, and DIFLEISURE) discussed in the previous section, or to avoid combining their values in a single "impact score." The same is true for EMODIFF (which reports whether the child had difficulties with emotions, concentration, behavior, or getting along with others) and DIFMOS (which reports the duration of such difficulties, if present). DIFBURDEN (which reports parents' answers to the question, "Do the difficulties put a burden on you or the family as a whole?") focuses on the effect of difficulties on family members other than the child. DIFBURDEN is thus excluded from the calculation of an "impact score" for the child, described in the previous section.

In the abbreviated version of the SDQ, which was part of the NHIS in 2002, 2005-2007, and 2010-2018. EMODIFF was the only element of the "impact supplement" from the SDQ-EX included in the survey. For 2008 forward, EMODIFF is the only element of the SDQ questionnaire included in the National Health Interview Survey.