Evidence-based assessment/Instruments/Strength and difficulties questionnaire

The Strengths and Difficulties Questionnaire (SDQ) is a behavioral screening questionnaire for children and adolescents ages 2 through 17 years old, developed by child psychiatrist Robert Goodman in the United Kingdom. Versions of it are available for use for no fee. The combination of its brevity and noncommercial distribution have made it popular among clinicians and researchers. There are more than 3000 peer reviewed articles using it that are indexed in PubMed alone. Overall, the SDQ has been proven to have satisfactory construct and concurrent validity across a wide range of settings and samples. It is considered a good general screening measure for attention problems, although the sensitivity and specificity are not both over .80 at any single cut score, so it should not be used by itself as the basis for a diagnosis of attention-deficit/hyperactivity disorder.

There are versions of the SDQ designed for use in different situations, including a short form, a longer form with an impact supplement, and a follow-up form designed for use after a behavioral intervention. The questionnaire takes 3–10 minutes to complete. There are now self-report (completed by the youth), parent-report, and teacher-report versions. A version designed for adults (age 18+ years) to fill out about themselves has also been developed. The SDQ has been translated into more than 80 languages, including Spanish, Chinese, Russian, and Portuguese.

General population norms are available for the USA and UK for some of the variations of the SDQ.

Scoring and interpretation
Respondents are asked to indicate whether a specific attribute is “not true”, “somewhat true”, or “certainly true”. There are four versions of the short form:


 * Three parent/teacher versions for children ages 2–4, 4-10, and 11-17,
 * One self-report version for children ages 11–17.

Scores on the attributes section range from 0-40, with prosocial behavior scale scores not included in the total score. All versions of the SDQ ask 25 questions sorted into 5 scales. Four of these are potential problems, and one is strength-related.


 * *Reverse scoring means that responses of “not true” receive 2 points, responses of “somewhat true” receive 1 point, and responses of “certainly true” receive 0 points.

Other scoring
The same 25 items are included in questionnaires for completion by the parents or teachers of 4- to 16-year-olds.

A slightly modified informant-rated version for the parents or nursery teachers of 2- to 4-year-olds. 22 items are identical, the item on reflectiveness is softened, and 2 items on antisocial behavior are replaced by items on oppositionality.

Questionnaires for self-completion by adolescents ask about the same 25 traits, though the wording is slightly different as it is in the first person (e.g. 'I often worry' instead of 'Many worries, often seems worried'). This self-report version is suitable for young people aged around 11-17, depending on their level of understanding and literacy.

B. An impact supplement
Several two-sided versions of the SDQ are available with the 25 items on strengths and difficulties on the front of the page and an impact supplement on the back. These extended versions of the SDQ ask whether the respondent thinks the young person has a problem, and if so, enquire further about chronicity, distress, impairment in everyday activities, and burden to others. This provides useful additional information for clinicians and researchers with an interest in psychiatric caseness and the determinants of service use.

C. Follow-up questions
The follow-up versions of the SDQ include not only the 25 basic items and the impact question, but also two additional follow-up questions for use after an intervention of after visits to a clinic: To increase the chance of detecting change, the follow-up versions of the SDQ ask about 'the last month', as opposed to 'the last six months or this school year', which is the reference period for the standard versions. Follow-up versions also omit the question about the chronicity of problems.
 * 1) How have the intervention / clinic visits changed the child's problems?
 * 2) Has the intervention helped in other ways, e.g. making the problems more bearable?

How to score the SDQ
The SDQ scoring site allows one to score paper copies of a parent, teacher and/or self-report SDQ free-of-charge, and generates a brief report. Briefly, each of the five scales of the SDQ are scored from 0-10, and one can add up four of these (emotional, conduct, hyperactivity and peer problems) to create a total difficulty score (range 0-40). One can also add the emotional and peer items together to get an internalizing problems score (range 0-20) and add the conduct and hyperactivity questions together to get an externalizing score (range 0-20).