Adolescence is a critical developmental period marked by heightened vulnerability to mental health problems, which affect approximately one in seven adolescents worldwide and contribute substantially to long-term individual and societal burden (WHO, 2024). Early identification of emotional, behavioral, and social difficulties is therefore essential, particularly in school and community settings. The Strengths and Difficulties Questionnaire (SDQ) is among the most widely used screening instruments for child and adolescent mental health, owing to its brevity, open-access availability, and multi-informant format. The SDQ comprises 25 items assessing five domains—emotional symptoms, conduct problems, hyperactivity/inattention, peer problems, and prosocial behavior—and has demonstrated utility comparable to longer instruments. Despite its widespread use and extensive cross-cultural application, persistent debate regarding the SDQ’s underlying factor structure raises important concerns about the validity and interpretability of its subscale scores, underscoring the need for continued psychometric evaluation.

Since its introduction in 2001, numerous studies across diverse cultural contexts have examined the SDQ’s factor structure, yielding mixed findings. While some investigations support the original five-factor model, many others report only moderate or poor fit, calling into question the construct validity of the subscale scores. Moreover, relatively few studies have focused specifically on adolescent samples. As noted by Goodman et al. (2010) the internal structure of the SDQ remains unresolved—a concern that persists more than a decade later.

In general, validation studies of the three-factor model have produced less favorable psychometric results than those of the five-factor solution (e.g., Karlsson et al., 2022). The bifactor model has emerged as another prominent alternative. Each SDQ item loads simultaneously on a general difficulties factor and on its respective domain-specific factor. This specification allows the general factor to capture shared variance across all items, while the specific factors retain residual variance unique to each domain. Accordingly, the bifactor model enables evaluation of whether the SDQ primarily reflects a broad, overarching difficulties construct and whether the subscales contribute distinct and meaningful variance beyond the general factor.

Across studies, bifactor models have frequently outperformed both five- and three-factor solutions in terms of global model fit (e.g., Murray et al., 2019). In many cases, the general difficulties factor accounted for the majority of item variance, whereas several specific factors—particularly peer problems and, in some studies, conduct problems—exhibited weak or unstable loadings. These findings suggest that the SDQ may function more reliably as a measure of overall psychosocial difficulties than as a multidimensional instrument capturing well-differentiated domains. However, results have not been uniform. Some studies have reported inadmissible or poorly fitting bifactor solutions (e.g., Duinhoven et al., 2019), often attributable to instability in weaker subfactors. Moreover, even when fit indices favor the bifactor model, concerns remain regarding the interpretability and reliability of specific factors with limited unique variance, as well as the practical utility of reporting subscale scores when most reliable variance is attributable to the general difficulties dimension.

The aim of the present study was to examine the underlying factor structure of the 25-item Turkish self-report SDQ for adolescents aged 11–17 years using CFA. Several theoretically grounded and empirically supported models were evaluated, including the original five-factor model, three-factor models, a second-order five-factor model, bifactor models specifying a general difficulties factor orthogonal to domain-specific factors, and models incorporating a method factor. Given the model misfit observed across CFA and ESEM solutions, Rasch measurement modeling was subsequently employed to examine item-level measurement properties. Rasch-based indices complemented the factor-analytic findings by providing a fine-grained evaluation of item functioning and identifying specific sources of misfit that may inform future scale refinement.

The data consisted of 1,458 adolescents aged 11 to 18. Of these, 38.27% were middle school students (Grades 5–8) and the remainder were high school students (Grades 9–11); Among the middle school students, 49.26% were female, and 50.0% of the high school students were female. The overall mean age was 14.14 years (SD= 1.96) All study procedures were approved by the university’s Human Subjects Review Board and were subsequently approved by the Turkish Ministry of National Education (MoNE). The MoNE decided schools from a list of schools/districts proposed by the researchers. Data were collected in May 2025 from X middle schools and Y high schools located in a cosmopolitan city near the researchers’ university. Paper-and-pencil questionnaires were administered to students by classroom teachers during regular instructional hours. Data were first screened for inattentive responding using multiple indicators. Assumptions of multivariate normality were examined in R using the following packages: psych (v2.5.6), Hmisc (v5.2-4), car (v3.1-3), and MVN (v6.2). All models were estimated with the lavaan package in R using the weighted least squares mean and variance–adjusted estimator (WLSMV) which is specifically designed for categorical or ordinal indicators and provides robust parameter estimates without assuming multivariate normality. Rasch analysis will be conducted in Winstep software

The present study evaluated the factorial validity of the scores obtained from SDQ by systematically comparing competing measurement models proposed in the literature, including method factor, five-factor, three-factor, second-order, and bifactor structures. Consistent with prior research, none of the tested models provided a fully adequate and theoretically coherent representation of the data without notable limitations. In the present study, method factor models converged but did not substantially alter fit indices or parameter estimates, suggesting that SDQ measurement problems are more plausibly attributable to substantive item content and domain characteristics rather than systematic method variance. The original five-factor model demonstrated marginal fit, consistent with numerous prior evaluations (e.g., Goodman et al., 2010; Karlsson et al., 2022). Persistent weaknesses were again evident for the Peer Problems subscale, which showed weak and heterogeneous factor loadings and low internal consistency, closely mirroring findings across diverse samples. Conduct Problems and Hyperactivity/Inattention also exhibited modest reliability and recurrent item instability, frequently requiring item removal, cross-loadings, or correlated residuals to achieve acceptable fit. Together, these patterns raise concerns regarding the conceptual coherence and measurement precision of several SDQ subscales. The three-factor model showed consistently poor fit, aligning with prior research favoring the five-factor structure despite its limitations. Second-order models failed to yield stable or adequate solutions, largely due to difficulties associated with the Peer Problems domain. Finally, bifactor models did not provide a satisfactory alternative: although sometimes yielding acceptable global fit, they were characterized by weak specific factor loadings and limited interpretability, calling into question the utility of a total difficulties score. The convergence of these findings with previous studies suggests that the measurement challenges identified here are not sample-specific anomalies but reflect enduring structural limitations of the SDQ with implications for construct validity and interpretability

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