European Child & Adolescent Psychiatry
9:271±276 (2000) Ó Steinkop€ Verlag 2000
H. Klasen
W. Woerner
D. Wolke
R. Meyer
S. Overmeyer
W. Kaschnitz
A. Rothenberger
R. Goodman
Accepted: 22 February 2000
Dr. H. Klasen
Department of Child and Adolescent
Psychiatry
St. George's Medical School, Tooting
GB ± London SW17 0RE
Dr. W. Woerner á Prof. Dr. A. Rothenberger
Child and Adolescent Psychiatry
University of GoÈttingen
von-Siebold Str. 5
D-37075 GoÈttingen
Prof. Dr. D. Wolke
University of Hertfordshire
Department of Psychology, College Lane
GB ± Hat®eld, Herts
AL10 9AB
Dr. R. Meyer
Lehrstuhl fuÈr Psychologie IV
RoÈntgenring 10
D-97074 WuÈrzburg
Dr. S. Overmeyer
Klinik fuÈr Kinder- und Jugendpsychiatrie
Friedrich-Schiller-UniversitaÈt
Philosophenstrasse 3-5
D-07740 Jena
Dr. W. Kaschnitz
UniversitaÈts Klinik fuÈr Kinder- und
Jugendheilkunde
Klinische Abteilung fuÈr Allgemein
PaÈdiatrie, Auenbruggerplatz 30
A-8036 Graz
Prof. Dr. R. Goodman (&)
Department of Child and Adolescent
Psychiatry, Institute of Psychiatry
De Crespigny Park
GB ± London SE5 8AZ
ORIGINAL CONTRIBUTION
Comparing the German Versions of the
Strengths and Dif®culties Questionnaire
(SDQ-Deu) and the Child Behavior Checklist
Abstract The Strengths and Diculties Questionnaire (SDQ) is a
brief behavioural screening questionnaire that can be completed in
about 5 minutes by the parents and
teachers of 4±16 year olds. The
scores of the English version correlate well with those of the considerably longer Child Behavior Checklist
(CBCL). The present study compares the German versions of the
questionnaires. Both SDQ and
CBCL were completed by the parents of 273 children drawn from
psychiatric clinics (N = 163) and
from a community sample
(N = 110). The children from the
community sample also ®lled in the
SDQ self-report and the Youth Self
Report (YSR). The children from
the clinic sample received an ICD-10
diagnosis if applicable. Scores from
the parent and self-rated SDQ and
CBCL/YSR were highly correlated
and equally able to distinguish between the community and clinic
samples, with the SDQ showing
signi®cantly better results regarding
the total scores. They were also
equally able to distinguish between
disorders within the clinic sample,
the only signi®cant di€erence being
that the SDQ was better able to
di€erentiate between children with
and without hyperactivity-inatten-
Introduction
The Strengths and Diculties Questionnaire is a brief
behavioural screening questionnaire which was devel-
tion. The study shows that like the
English originals, the SDQ-Deu and
the German CBCL are equally valid
for most clinical and research purposes.
Key words Child psychopathology ±
psychometrics ± questionnaires ±
validity ± German
oped in England (8) and has been translated into over
40 languages. It asks about 25 attributes, some
positive and some negative. The items, which have
been selected on the basis of contemporary diagnostic
272
European Child & Adolescent Psychiatry, Vol. 9, No. 4 (2000)
Ó Steinkop€ Verlag 2000
criteria as well as factor analysis, are divided between
®ve scales of ®ve items each, generating scores for
Conduct
Problems,
Hyperactivity-Inattention,
Emotional Symptoms, Peer Problems, and Prosocial
Behaviours. All items of the ®rst four subscales are
summed up to generate a Total Diculties Score. The
same questionnaire can be completed in about ®ve
minutes by parents or teachers of children aged 4 to
16. There is also a self-report version (10) for those
aged 11 and above. An extended version assesses
impact on social and educational function, distress,
and burden on others (9).
The validity of the English and Finnish instrument
has been shown in various studies (8±11, 13). Translated
versions are currently being validated in various countries including Spain, Bangladesh and Brazil. The factor
structure has recently been con®rmed using the Swedish
translation (16). Although the German version of the
questionnaire has been available since 1997 and is
already being used both in research and clinical practice,
a systematic validation has not yet taken place.
Since the German translation of the longer established Child Behavior Checklist (CBCL; 1, 4) has been
extensively used and validated in large epidemiological
studies (5, 6, 14, 15), it is clearly important to compare
the properties of these two measures. In such comparisons, the CBCL can serve as a gold standard against
which the considerably shorter SDQ can be measured. A
previous study showed that the original English versions
of the SDQ and CBCL were highly correlated and
generally performed similarly, though the SDQ seemed
superior as a measure of inattention/hyperactivity (11).
The present study has ®ve aims. Firstly, we determine how well the German versions of the parent-rated
SDQ and the CBCL correlate. Secondly, we examine
the correlations of the German self-report SDQ and the
Youth Self Report (2). Thirdly, we investigate the level
of parent-child agreement for both questionnaires.
Fourthly, we examine how well both German SDQs
and CBCLs are able to distinguish between low-risk
children in the community and high-risk children with
a relevant psychiatric diagnosis. Finally, we explore
within a clinic sample how well the questionnaires are
able to distinguish between the type of psychiatric
disorder.
Method
Sample
Questionnaires were administered to a total of 273
children drawn from clinic and community samples.
Parent-rated questionnaires were available on all subjects, but self-rated questionnaires were only available
for the community sample.
The clinic sample comprised 163 children seen in
three psychiatric centres in Germany and Austria
(Departments of Child and Adolescent Psychiatry at
the Universities of GoÈttingen, Freiburg and Graz).
Questionnaires were completed prior to clinical interventions. Within the clinic sample, 124 children were
boys (76%) and 39 were girls (24%); 28 children (18%)
were inpatients and 135 were outpatients (82%); 52% of
the children were between 4 and 10 years old, while 42%
were between 11 and 16. Of the 163 children in the clinic
sample, 49 (30%) had an emotional disorder, 42 (26%)
had a conduct disorder and 65 (40%) had a hyperactivity disorder. Comorbidity was common, with 39 children
(24%) having two or more of these disorders, most
commonly the combination of conduct and hyperactivity disorder. A total of 52 children (32%) had none of
these three common disorders; they had other disorders
(e.g. enuresis or psychosis) or were referred for other
reasons (e.g. abuse).
The community sample comprised 110 children from
a cohort of children that had been investigated since
birth (18, 19). All children were born in 1985 in Bavaria
(age 12 to 13 at the point of investigation); 52% of them
were boys and 47% were girls.
Measures
The German translations of the CBCL and YSR (4)
were administered to all parents and to the children from
the community sample. The SDQ was translated by a
German child psychiatrist and by a professional translator, subsequently incorporating improvements suggested by colleagues and early piloting. Parent, teacher
and self-report versions of the SDQ-Deu can be downloaded from the internet (http://www.sdqinfo.com). All
questionnaires were scored in the standard manner (1, 2,
4, 8, 10).
In the clinic sample, clinicians assigned the children
an ICD-10 diagnosis (20) on the basis of detailed clinical
assessment. To avoid small cell sizes, diagnoses were
combined into three broad groupings for analysis:
oppositional-conduct disorders, hyperactivity-inattention disorders and emotional disorders. As some ICD
diagnoses represent mixed disorders (e.g. hyperkinetic
conduct disorder) some children were included in more
than one group. Other children in the clinic sample were
not included in any of the three groups (see sample
description above).
Statistical analysis
Given the non-normal nature of some of the distributions, correlations were calculated using Spearman's rho
coecients, while comparisons of means were carried
H. Klasen et al.
Comparing the German SDQ and CBCL
out using Mann±Whitney U tests. Correlations were
performed with regard to the total score and the
problem scales. The Prosocial Scale of the SDQ and
the Competence Scale of the CBCL were not compared
since they di€er so markedly in content even though they
do share a focus on positive attributes.
In order to determine how well both the SDQ-Deu
and the German CBCL are able to distinguish between
the community sample and children with a relevant
ICD-10 diagnosis, and between diagnosed children and
a clinic sample, we used receiver operating characteristics (ROC) curves. Using analyses of ROC curves to
compare the discriminant validity of the two questionnaires does not depend on the representativeness of the
two samples; it assumes only that the relevant psychiatric disorder is more common in the high-risk than in
the low-risk group. Since the ROC curves for the SDQ
and CBCL were derived from the same set of subjects,
statistical comparisons of the areas under these ROC
curves took their paired nature into account (12).
Comparisons of correlations were performed using
structural equation modelling (EQS, BMDP Statistical
Software) to account for the paired nature of the data.
For example, when the parent-child correlation for the
SDQ di€ered from the corresponding CBCL-YSR
correlation, the signi®cance of this di€erence was
examined by comparing two di€erent structural equation models: one allowing the correlations to be di€erent
and the other constraining the correlations to be equal.
The di€erence in correlations was signi®cant if the
goodness of ®t was signi®cantly poorer when the
correlations were forced to be equal (7).
For the analyses presented in Table 4 comparing
community and clinic samples, all 110 community
subjects were included in each comparison, while the
number of clinic subjects varied according to comparison. All clinic cases were included for total scores and
peer/social problems. However only children with the
relevant diagnosis were included in the other comparisons, e.g. the ROC analysis for emotional symptoms
involved a comparison between all community subjects
Table 1 Mean SDQ scores by
gender and sample
SDQ scale
273
and those clinic cases with an emotional disorder
(excluding clinic cases who did not have an emotional
disorder).
Results
Mean SDQ scores
Table 1 presents the mean SDQ scores for the community and clinic samples, showing the results for males
and females separately. The di€erence between clinic
and community samples was highly signi®cant for each
score for both genders (p<0.001).
The correlation of German SDQ and CBCL/YSR
The ®rst two columns of Table 2 show the correlation of
corresponding SDQ and CBCL scores. The two questionnaires correlated highly with regard to total scores as
well as subscales. All correlations were statistically
signi®cant at the 0.001 level. We also compared how
well the questionnaires correlate when children ®ll them
in themselves (Table 2, third column). The self-report
questionnaires were only completed by children in the
community sample. As with the parent questionnaires,
the two di€erent self-report questionnaires correlate
well. All results were signi®cant at the 0.001 level.
Comparing parent reports and self-reports
Within the community sample, children ®lled in both the
self-report SDQ and the YSR, while their parents ®lled
in the SDQ and the CBCL. We examined how well
children and parents agree regarding their symptoms
when using the two questionnaires. As shown in Table 3,
children and parents agree moderately well (rho between
0.36 and 0.64), with similar correlations for both sets of
measures. None of the di€erences in correlations are
Mean score (SD)
Males
Total diculties
Emotional symptoms
Conduct problems
Hyperactivity
Peer problems
Prosocial behaviour
Female
Community
(N = 58)
Clinic
(N = 124)
Community
(N = 52)
Clinic
(N = 39)
6.6
1.3
1.0
2.8
1.5
7.6
17.4
3.4
4.0
6.5
3.5
6.1
5.1
1.8
0.7
1.9
0.7
8.9
14.9
4.3
3.3
4.6
2.7
6.4
(4.9)
(1.5)
(1.4)
(2.4)
(2.0)
(2.0)
(6.5)
(2.5)
(2.4)
(2.6)
(2.5)
(2.1)
(4.5)
(1.7)
(1.1)
(2.1)
(1.1)
(1.3)
All community-clinic comparisons signi®cant at p<0.001 using Mann±Whitney U test
(6.7)
(2.6)
(2.2)
(2.6)
(2.5)
(2.4)
274
European Child & Adolescent Psychiatry, Vol. 9, No. 4 (2000)
Ó Steinkop€ Verlag 2000
Table 2 Correlations between German SDQ and CBCL/YSR
scores
Table 4 Ability of parent-rated SDQ and CBCL scores to distinguish between community and clinic samples
Problem scale
Community Clinic
parents
parents
(N = 110) (N = 163)
Community
youth
(N = 110)
Problem scale
Total score
Emotional/Internalising
Conduct/Externalising
Hyperactivity/Attention
problems
Peer/Social
0.78
0.69
0.60
0.76
0.82
0.73
0.81
0.68
0.77
0.73
0.59
0.78
0.61
0.68
0.58
All correlations signi®cant at p<0.001
Total Score
Emotional/Internalising
Conduct/Externalising
Hyperactivity/Attention
problems
Peer/Social
Area under curve (SE) ±
comparing community and
clinic1 samples
SDQ
CBCL
0.91
0.85
0.97
0.94
0.87
0.88
0.96
0.92
(0.02)
(0.04)
(0.01)
(0.02)
0.78 (0.03)
p
(0.02)
(0.03)
(0.02)
(0.02)
**
NS
NS
NS
0.81 (0.03)
NS
1
signi®cant, i.e., neither of the questionnaires shows a
comparative advantage or disadvantage with regard to
parent-child agreement.
For all comparisons, N = 110 for community. For clinic cases,
N = 163 for total and peer/social scores, N = 49 for emotional/
internalising, N = 42 for conduct/externalising, and N = 65 for
hyperactivity/inattention, please see method section
** p < 0.01 for z test for comparing area under ROC curves
derived from the same subjects
NS not signi®cant
Ability to distinguish between community
and clinic samples
The ability of di€erent SDQ and CBCL scores to
distinguish between community and clinic subjects was
examined using receiver operating characteristics (ROC)
curves, employing the area under the curve (AUC) as the
index of discriminant ability (Table 4). As a guide to
interpretation, the area under the curve would be 1.0 for
a measure that discriminated perfectly, and 0.5 for a
measure that discriminated with no better than chance
accuracy. Both SDQ and CBCL show good discriminant
validity. With regard to the subscales, neither of the
questionnaires shows any signi®cant advantage. However, with respect to the total score, the SDQ-Deu is
signi®cantly better able to distinguish between the
community and clinic sample than the German CBCL,
though the magnitude of the di€erence is small.
Ability to distinguish between disorders
within a clinic sample
The ®nal analysis addresses the question of how useful
the two questionnaires are when used within a clinical
Table 3 Correlations between parent and self-reports (community
sample, N = 110)
Problem scale
SDQ
CBCL
Total score
Emotional/Internalising
Conduct/Externalising
Hyperactivity/Attention
problems
Peer/Social
0.60
0.59
0.36
0.64
0.53
0.58
0.38
0.57
0.57
0.44
sample. Did the emotional, conduct, and hyperactivity
scores discriminate within the clinic sample between
patients with di€erent sorts of disorders? This was also
examined using the area under ROC curves (Table 5).
For example, how well did the SDQ emotional score or
the CBCL internalising score discriminate between
patients with emotional disorders and psychiatric controls, i.e. psychiatric patients who did not have an
emotional disorder. There is again little di€erence in the
performance of the two questionnaires except in the case
of hyperactivity-inattention, where the SDQ performed
signi®cantly better. It is noteworthy that the questionnaires were not as good at discriminating between
di€erent types of disorder (Table 5) as they were at
distinguishing between the clinic and community sample
(Table 4). When the analyses shown in Table 5 were
repeated separately for 4±10 year olds and 11±16 year
olds, the pattern of ®ndings was unchanged.
Discussion
As was the case for the English originals (11) and for the
Finnish versions (13), the German versions of the
Strengths and Diculties Questionnaire and the Child
Behavior Checklist correlated highly with each other.
This was the case both for the parent-rated as well as for
the self-rated questionnaires. Both questionnaires were
able to distinguish between children drawn from community and clinic samples very well, while they both
performed less well in distinguishing between di€erent
types of disorder within a clinic sample. The equivalence
between the two questionnaires is striking as the SDQ is
only about a ®fth the length of the CBCL.
H. Klasen et al.
Comparing the German SDQ and CBCL
Table 5 Ability of scores to
distinguish between di€erent
types of disorders within the
clinic sample (N = 163)
Problem scale
Emotional/Internalising
Conduct/Externalising
Hyperactivity/Attention
problems
275
Comparing clinic cases
with and without:
(N with/without)
Area under curve (SE)
p
SDQ
CBCL
Emotional disorder
(49/114)
Conduct disorder
(42/121)
Hyperactivity disorder
(65/98)
0.72 (0.05)
0.75 (0.04)
NS
0.81 (0.04)
0.83 (0.04)
NS
0.77 (0.03)
0.65 (0.04)
**
** p < 0.01 for z test for comparing area under ROC curves derived from the same subjects
NS not signi®cant
Other things being equal, shorter scales are usually
less reliable than longer scales (17). In this instance,
however, the brevity of the SDQ did not reduce its
validity. While most of the di€erences between SDQDeu and German CBCL did not reach the signi®cance
level, in the two instances where they did, the SDQ
performed better than the CBCL. Thus, with regard to
total scores the SDQ was better able than the CBCL to
distinguish between community cases and clinic cases.
Within the clinic sample, the SDQ performed better than
the CBCL in picking up children with an ICD-10
diagnosis of hyperkinesis, in line with previous ®ndings
showing that interview measures of hyperactivity correlate better with the SDQ hyperactivity score than with
the CBCL attention problem score (11).
The results of this study are necessarily preliminary.
The study is limited by the fact that the community
children were all drawn from one age cohort, while the
children in the clinic sample spanned a larger age range.
It will obviously be important to replicate these ®ndings
on a broader age range, using diverse clinical and
community samples. It is unlikely, however, that these
studies will arrive at di€erent conclusions, since English
(11) and Finnish studies (13) using diverse samples with
a broader age range arrived at similar conclusions.
Further studies could also compare the informant-rated
SDQ completed by teachers with the Teacher Report
Form (3) and examine the value of the impact scores of
the SDQ (9).
Pending larger-scale studies, the current ®ndings
suggest that the two questionnaires are comparable in
many ways. Both of them are therefore suited for many
purposes. As Tables 4 and 5 have shown, the questionnaires are much better at distinguishing between a
community sample and psychiatric cases than at discriminating between di€erent sorts of disorder within a
clinic sample. This makes the instruments particularly
useful as screening instruments or as research tools for
epidemiological studies. Within the clinic population,
the use of either questionnaire as a diagnostic tool is
limited, though they can be used before and after
treatment to audit outcome, or they can help in
prioritising cases.
In some respects, however, the two questionnaires
have di€erent strengths. The brevity of the SDQ and its
low cost in administration as well as evaluation make it
a particularly useful instrument for large epidemiological studies as well as for screening of large groups of
low-risk children. The SDQ does, however, have fewer
subscales than the CBCL and does not ask about less
common symptoms such as compulsions, hallucinations,
or sexual problems. Consequently, the CBCL might be
better suited for studies that require a more detailed
assessment of a broader range of symptoms. The SDQ
and CBCL serve somewhat di€erent purposes, though
both questionnaires seem equally valid for most clinical
and research applications.
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