These follow-up questions asked how much these difficulties upset or distressed the child (DIFUPSET, whether they interfered with the child's everyday life (DIFHOME, DIFFRIEND, DIFLEARN, DIFLEISURE), and whether they burdened the child's family (DIFBURDEN).

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.

DIFMOS 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 second section of the SDQ-EX, which includes DIFMOS, as the "Impact Supplement."

In the 2001 and 2003-2004 NHIS, if parents said (in EMODIFF) that the child had minor, definite, or severe difficulties with emotions, concentration, behavior, or getting along with others, they were asked how long the difficulties had been present (DIFMOS). If the reported duration of these difficulties was one month or longer, interviewers asked further follow-up questions that 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)

DIFUPSET was based on the question, "Do the difficulties upset or distress your child?" The remaining four variables were based on query, "Do the difficulties interfere with your child's everyday life in the following areas: Home life? Friendships? Classroom learning? Leisure activities?"

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, in DIFMOS, 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 difficulties lasting "less than one month" (code 1 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: