Development of a computerized adaptive test for Schizotypy assessment.

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Development of a Computerized Adaptive Test for Schizotypy Assessment Eduardo Fonseca-Pedrero1,3*, Luis Fernando Mene´ ndez2, Mercedes Paino2,3, Serafı´n Lemos-Gira´ ldez2,3, Jose´ Mun˜ iz2,3 1 Department of Educational Sciences, University of La Rioja, La Rioja, Spain, 2 Department of Psychology, University of Oviedo, Oviedo, Spain, 3 Center for Biomedical Research in the Mental Health Network (CIBERSAM), Madrid, Spain Abstract Background: Schizotypal traits in adolescents from the general population represent the behavioral expression of liability for psychotic disorders. Schizotypy assessment in this sector of population has advanced considerably in the last few years; however, it is necessary to incorporate recent advances in psychological and educational measurement. Objective: The main goal of this study was to develop a Computerized Adaptive Test (CAT) to evaluate schizotypy through ‘‘The Oviedo Questionnaire for Schizotypy Assessment’’ (ESQUIZO-Q), in non-clinical adolescents. Methods: The final sample consisted of 3,056 participants, 1,469 males, with a mean age of 15.9 years (SD = 1.2). Results: The results indicated that the ESQUIZO-Q scores presented adequate psychometric properties under both Classical Test Theory and Item Response Theory. The Information Function estimated using the Gradual Response Model indicated that the item pool effectively assesses schizotypy at the high end of the latent trait. The correlation between the CAT total scores and the paper-and-pencil test was 0.92. The mean number of presented items in the CAT with the standard error fixed at #0.30 was of 34 items. Conclusion: The CAT showed adequate psychometric properties for schizotypy assessment in the general adolescent population. The ESQUIZO-Q adaptive version could be used as a screening method for the detection of adolescents at risk for psychosis in both educational and mental health settings. Citation: Fonseca-Pedrero E, Mene´ndez LF, Paino M, Lemos-Gira´ldez S, Mun˜ iz J (2013) Development of a Computerized Adaptive Test for Schizotypy Assessment. PLoS ONE 8(9): e73201. doi:10.1371/journal.pone.0073201 Editor: Redhwan Ahmed Al Naggar, Population Health and Preventive Medicine, Malaysia Received April 18, 2013; Accepted July 15, 2013; Published September 3, 2013 Copyright: ß 2013 Fonseca-Pedrero et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was funded by the Spanish Ministry of Science and Innovation (MICINN) and by the Instituto Carlos III, Center for Biomedical Research in the Mental Health Network (CIBERSAM). Project references: PSI 2011-28638 and PSI 2011-23818. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: Introduction Schizotypy is a complex construct which is intimately related at the historical, genetic, neurodevelopmental, neurocognitive, social, emotional and psychophysiological levels to psychotic disorders [1–3]. Independent follow-up studies indicate that adolescents from the general population who report schizotypal experiences such as magical thinking, hallucinatory experiences, delusional ideation and/or anhedonia have a greater risk of transiting toward schizophrenia-spectrum disorders [4–9]. Also, the subclinical expression of the psychosis phenotype has been associated with the same risk factors related to schizophrenia (e.g., cannabis use, urbanicity, trauma, etc.) conferring aetiological validity on this construct and suggesting a possible continuity between the clinical and the subclinical psychosis phenotypes [10]. In this sense, schizotypal traits in adolescence might represent the behavioral expression of vulnerability for psychotic disorders in the general population [11,12]. A current line of research in the psychosis field is based on the idea that early detection, prevention and intervention in young people at risk for psychosis could mitigate or reduce the impact the disorder can cause on personal, familial, work and social spheres [13,14]. Among other aspects, this fact has driven the construction and validation of measurement instruments for the assessment of schizotypy at early ages [15]. The aim of the psychometric highrisk paradigm is the detection, by means of self-reports and based on their score profiles, of those participants at risk for psychosis in the future [16,17]. This paradigm is considered a reliable, valid and useful method for the psychometric detection of individuals at risk for psychosis. In comparison to other techniques, the use of these tools constitutes a rapid, efficient and noninvasive method of assessment. Moreover, it allows the study of symptoms that are similar to those found in patients with schizophrenia while avoiding the confounding effects frequently found in these individuals (e.g., medication or stigmatization) [6,17,18]. The detection of these types of individuals at risk for psychosis, whether in clinical or educational settings, requires having adequate measurement instruments that allow us to make solid and well-founded decisions based on the data. The Wisconsin Schizotypy Scales [19] and the Schizotypal Personality Question- PLOS ONE | 1 September 2013 | Volume 8 | Issue 9 | e73201 Computerized Adaptive Test naire [20] are among the most utilized tools in the literature for the assessment of this construct in adult populations. Likewise, and given that adolescence is a developmental period of special risk for psychosis and related disorders [21,22], efforts have also been directed at the assessment of schizotypal experiences and traits in this age group. Good examples of these self-reports are the Junior Schizotypy Scales [23], or The Oviedo Schizotypy Assessment Questionnaire (ESQUIZO-Q) [24]. The cited self-reports have presented adequate psychometric properties under Classic Test Theory (CTT); however, it is necessary to rigurously advance in the assessment of this construct with the incorporation of psychometric advances such as differential item functioning, measurement invariance across age or cultures [25,26] or Item Response Theory (IRT) [27]. IRT originates as a complementary psychometric model and offers many advantages over CTT [28,29]. The IRT approach along with computer implementation has changed the psychological assessment panorama with new forms of measurement emerging, such as Computerized Adaptive Testing (CAT) [30– 32]. In this regard, an interesting expansion has taken place as shown by the CATs constructed in diverse areas as education (e.g., English) [33], health (e.g., quality of life) [34,35] or psychopathology (e.g., depression, personality) [36,37]. CAT involves the computerized administration of a test in which each item is dynamically selected from a pool of items until a pre-specified measurement precision is reached. CAT successively selects items in order to maximize the precision of the measurement instrument based on what is known about the person from previous items. The essential idea is that when adjusting the items to the competency (or latent trait) of the test taker, once these are calibrated according to an IRT model far fewer items are needed to assess individuals with precision in comparison to paper-andpencil tests. Thus, items and time are saved through the use of precision and efficiency. In addition, this way of proceeding further motivates the assessed subjects as the items they must respond to are neither too easy nor too difficult, but rather are adjusted to their latent-construct level [38]. Moreover, through IRT, an Item Characteristic Curve (ICC) is constructed for each item. This curve, or trace line, reflects the probability of the person’s response to each item and his/her level on the latent construct (e.g., schizotypy) measured by the scale. Furthermore, IRT allows us to estimate the contribution each item makes to the assessment for each level of the latent construct: the Information Function. Standard error is inversely linked to the information distribution used, and hence, the estimated standard error is available for each assessment. To date, a CAT for schizotypy assessment in the general adolescent population has not been developed. Advances in the measurement field, along with IRT, improve the precision in the evaluation of this construct as well as its comprehension. Likewise, the incorporation of more robust statistical models may allow improvement in the detection procedures for this group of participants at psychometric risk for psychosis. Within this research context, the main goal of this study was to analyze the psychometric properties and efficiency of a hypothetical CAT to assess schizotypy, via ESQUIZO-Q, in a representative sample of adolescents from the general population. Its psychometric quality and efficiency was examined in its two modalities, both for a polytomous response format as well as a dichotomous response format, comparing the estimates obtained with the classic paperand-pencil test to those obtained with the CAT. Methods Participants Two stratified random cluster samplings were carried out at the classroom level in a population of approximately 37,000 students selected from the Principality of Asturias (a region in northern Spain) during two academic years (2008–2009 and 2009–2010). Other data from this research has been published elsewhere [24,39]. The students were from various public and statesubsidized secondary schools and vocational training centres, as well as from a wide range of socio-economic levels. The strata were created on the basis of geographical zone (East, West, Centre and Mining area) and educational stage (compulsory – to age 16– and post-compulsory). The likelihood of a school being included was directly proportional to the number of students in it. The final sample was made up of N = 3,056 participants, 1,496 boys (48.1%). The mean age was 15.9 years (SD = 1.2), with an age range of 14 to 18 years. The sample distribution according to age was the following: 14 year olds (N = 400; 13.1%), 15 year olds (N = 780; 25.5%), 16 year olds (N = 885; 29%), 17 year olds (N = 703; 23%) and 18 year olds (N = 288; 9.4%). Instruments The Oviedo Schizotypy Assessment Questionnaire (ESQUIZO-Q) [24] is a self-report composed of 51 items in a 5-point Likert-type response format (1 = ‘‘completely disagree’’; 5 = ‘‘completely agree’’) designed to assess schizotypal traits and experiences in adolescents. The ESQUIZO-Q is based on the diagnostic criteria proposed in the DSM-IV-TR [40] and on Meehl’s schizotaxia model [41] regarding genetic predisposition to schizophrenia. The ESQUIZO-Q comprises a total of 10 subscales: Ideas of Reference, Magical Thinking, Unusual Perceptual Experiences, Odd Thinking and Language, Paranoid Ideation, Physical Anhedonia, Social Anhedonia, Odd Behavior, Lack of Close Friends and Excessive Social Anxiety. These subscales are grouped into three general dimensions: Reality Distortion, Anhedonia, and Interpersonal Disorganization. The psychometric properties of the ESQUIZOQ have been extensively analyzed under CTT. The general schizotypy dimensions have been empirically derived through exploratory factor analyses and a rigorous process of item treatment according to international standards. No item in the ESQUIZO-Q showed differential functioning for gender. Internal consistency levels for the ESQUIZO-Q subscales ranged from 0.62 to 0.90 [39,42]. Items of the ESQUIZO-Q are available as Supporting Information S1. The Oviedo Infrequency Scale (INF-OV) [43] is a 12-item self-report with a 5-point Likert-type rating scale format (1 = ‘‘completely disagree’’; 5 = ‘‘completely agree’’). Its goal is to detect participants who respond randomly, pseudorandomly or dishonestly on self-reports (e.g., ‘‘The distance between Madrid and Barcelona is greater than between Madrid and New York’’). This type of self-report is frequently used in studies on psychosis proneness in both clinical and non-clinical populations. Once the answers were dichotomized, students with more than 2 incorrect responses on this self-report were removed from the study. A total of 94 participants presented a score above two points on the INF-OV. No statistical differences were found between the group of participants who obtained more than two points on the INF-OV and the final sample. Ethic Statement Written informed parental/guardian consent was obtained for all minors involved in the study. The study is part of a wider investigation on the detection and early intervention in psychological disorders in adolescence and was approved by the Research PLOS ONE | 2 September 2013 | Volume 8 | Issue 9 | e73201 Computerized Adaptive Test and Ethics Committees at the University of Oviedo and the Department of Education of the Principality of Asturias. Procedure The administration of the questionnaires was conducted in a collective manner in groups of 10–35 students during the school schedule and in a room prepared for this purpose. The study was presented to participants as an investigation regarding diverse personality characteristics, assuring participants of the confidentiality of their answers as well as the voluntary nature of their participation. The completion of the questionnaires was conducted under the supervision of a researcher at all times. Data Analyses First, the descriptive statistics for the ESQUIZO-Q subscales and second-order dimensions were calculated under CTT. Then, the calibration of the parameters of the 51 items in the ESQUIZO-Q under IRT was performed. For this purpose, Samejimas Graded Response Model (GRM) [44] and the two parameter logistic model (2PL) [45] were used. For the psychometric calibration of the ESQUIZO-Q items, several analyses were conducted: a) unidimensionality; b) local independence; c) monotonicity; d) model fit of GRM; and e) DIF by gender. In regard to the unidimensionality of the ESQUIZO-Q items, it can be assumed that the original 51-item pool is not unidimensional. This fact will negatively influence the psychometric functioning of the CAT, which is based on the unidimensionality assumption. In this sense, several analyses were performed using the item bank. First, 51 items were calibrated, and second, 9 items and then 2 items were removed successively and iteratively depending on the fit to the data, the standard error estimation and inspection of the ICC. From a psychometric viewpoint, it is interesting to analyze test scores under a dichotomous-type and Likert format as it can be observed that the number of response categories of items affects the metric properties of the measurement instruments [46,47]. At the same time, in psychopathology measures, the response format that is more frequently used is the dichotomous type. The study of both types of formats allows us to make comparisons and observe levels of precision under CTT and IRT. In this study, the Likert format responses were dichotomized once the ESQUIZO-Q was administered (values 1–3 codified as ‘‘0’’ and values 4–5 as ‘‘1’’). The value h (theta) represents participants scores on the latent construct (schizotypy), parameter a (or slope) is related to the items discriminative power and parameter b (or location) to item threshold or difficulty level. A steeper slope indicates a closer relationship to the construct and therefore a more discriminating item. The larger the location parameter, the more of the measured construct a respondent must have to endorse that item. In the GRM, the number of estimated b parameters is equal to the item response category number minus one. In an item with a Likert response format with five options, the number of estimated b(k) parameters would be four. Each b(k) parameter indicates the probability of stepping from a lower category to a higher category. The 2PL model is used to calibrate the items of a dichotomous nature (e.g., Yes/No). The GRM is a model of IRT for polytomous data, and is a generalization of the 2PL model. In the 2PL model, discrimination parameter a and difficulty parameter b can also be estimated. Given that it is utilized for dichotomous models, the estimated number of parameter b is one. Finally, with respect to CATs, a simulation study was conducted. First, we used our own software with client-server technology for the implementation of two algorithms, one for polytomous data and another for dichotomous data [28]. The algorithm, which is common to both models, behaves in the following manner: 1) initially, we start from an estimated b parameter (1) which we assume as the population measure; 2) with the aim of estimating the following h value, the item that provides the greatest information value for this h is selected and is presented to the participant to be responded to; 3) once we obtain the response of the participant, it is used to obtain, through the Maximum Likelihood procedure [48], a new estimation of h as well as the corresponding standard error estimation (SE); and 4) steps 2 and 3 are repeated until the SE value is below an established value, usually 0.30. The criteria SE = 0.30 corresponds to a reliability of p = 0.9 (p = 1-SE2) [49]. Second, the study was performed using CAT in its two modalities, dichotomous and polytomous. Also, we used two stopping rule criteria (SE ,0.30; SE ,0.50) for illustrative purposes. The stopping rule used was the pre-specified level of measurement precision. The incorporation of the two stopping rule cut-offs allows us to examine the degradation effect in the functioning of the CAT. It is obvious that enfocar la importancia de la producción mediática de los niños en su descubrimiento del mundo, sobre todo utilizando el periódico escolar y la imprenta. Asimismo las asociaciones de profesores trabajaron en esta línea e incluso la enseñanza católica se comprometió desde los años sesenta realizando trabajos originales en el marco de la corriente del Lenguaje Total. Páginas 43-48 45 Comunicar, 28, 2007 En el ámbito de los medios, también desde el principio del siglo XX hay ciertas corrientes de conexión. Pero es a lo largo de los años sesenta cuando se constituyeron asociaciones de periodistas apasionados por sus funciones de mediadores, que fomentaron la importancia ciudadana de los medios como algo cercano a los jóvenes, a los profesores y a las familias. Así se crearon la APIJ (Asociación de Prensa Información para la Juventud), la ARPEJ (Asociación Regional de Prensa y Enseñanza para la Juventud), el CIPE (Comité Interprofesional para la Prensa en la Escuela) o la APE (Asociación de Prensa y Enseñanza), todas ellas para la prensa escrita Estas asociaciones fueron precedidas por movimientos surgidos en mayo de 1968, como el CREPAC que, utilizando películas realizadas por periodistas conocidos, aclaraba temas que habían sido manipulados por una televisión demasiado próxima al poder político y realizaba encuentros con grupos de telespectadores. cipio del siglo XX, y nos han legado textos fundadores muy preciados, importantes trabajos de campo y muchos logros educativos y pedagógicos. La educación en medios ha tenido carácter de oficialidad de múltiples maneras, aunque nunca como una enseñanza global. Así la campaña «Operación Joven Telespectador Activo» (JTA), lanzada al final de los años setenta y financiada de manera interministerial para hacer reflexionar sobre las prácticas televisuales de los jóvenes, la creación del CLEMI (Centro de Educación y Medios de Comunicación) en el seno del Ministerio de Educación Nacional en 1983, la creación de la optativa «Cine-audiovisual» en los bachilleratos de humanidades de los institutos en 1984 (primer bachillerato en 1989) y múltiples referencias a la educación de la imagen, de la prensa, de Internet. La forma más visible y rápida de evaluar el lugar de la educación en medios es valorar el lugar que se le ha reservado en los libros de texto del sistema educa- 2. Construir la educación en los medios sin nombrarla El lugar que ocupa la edu- La denominación «educación en medios», que debería cación en los medios es muy ambiguo, aunque las cosas están cambiando recientemente. entenderse como un concepto integrador que reagrupase todos los medios presentes y futuros, es a menudo percibida En principio, en Francia, co- por los «tradicionalistas de la cultura» como una tendencia mo en muchos otros países, la educación en los medios no es hacia la masificación y la pérdida de la calidad. una disciplina escolar a tiempo completo, sino que se ha ido conformado progresivamente a través de experiencias y reflexiones teóricas que han tivo en Francia. Una inmersión sistemática nos permi- permitido implantar interesantes actividades de carác- te constatar que los textos oficiales acogen numerosos ter puntual. Se ha ganado poco a poco el reconoci- ejemplos, citas, sin delimitarla con precisión. miento de la institución educativa y la comunidad es- colar. Podemos decir que ha conquistado un «lugar», 3. ¿Por qué la escuela ha necesitado casi un siglo en el ámbito de la enseñanza transversal entre las dis- para oficilializar lo que cotidianamente se hacía en ciplinas existentes. ella? Sin embargo, la escuela no está sola en esta aspi- Primero, porque las prácticas de educación en me- ración, porque el trabajo en medios es valorado igual- dios han existido antes de ser nombradas así. Recor- mente por el Ministerio de Cultura (campañas de foto- demos que no fue hasta 1973 cuando aparece este grafía, la llamada «Operación Escuelas», presencia de término y que su definición se debe a los expertos del colegios e institutos en el cine ), así como el Minis- Consejo Internacional del Cine y de la Televisión, que terio de la Juventud y Deportes que ha emprendido en el seno de la UNESCO, definen de esta forma: numerosas iniciativas. «Por educación en medios conviene entender el estu- Así, esta presencia de la educación en los medios dio, la enseñanza, el aprendizaje de los medios moder- no ha sido oficial. ¡La educación de los medios no apa- nos de comunicación y de expresión que forman parte rece oficialmente como tal en los textos de la escuela de un dominio específico y autónomo de conocimien- francesa hasta 2006! tos en la teoría y la práctica pedagógicas, a diferencia Este hecho no nos puede dejar de sorprender ya de su utilización como auxiliar para la enseñanza y el que las experiencias se han multiplicado desde el prin- aprendizaje en otros dominios de conocimientos tales Páginas 43-48 46 Comunicar, 28, 2007 como los de matemáticas, ciencias y geografía». A pe- mente en todas las asignaturas. Incluso los nuevos cu- sar de que esta definición ha servido para otorgarle un rrículos de materias científicas en 2006 para los alum- reconocimiento real, los debates sobre lo que abarca y nos de 11 a 18 años hacen referencia a la necesidad no, no están totalmente extinguidos. de trabajar sobre la información científica y técnica y En segundo lugar, porque si bien a la escuela fran- el uso de las imágenes que nacen de ella. cesa le gusta la innovación, después duda mucho en Desde junio de 2006, aparece oficialmente el tér- reflejar y sancionar estas prácticas innovadoras en sus mino «educación en medios» al publicar el Ministerio textos oficiales. Nos encontramos con una tradición de Educación los nuevos contenidos mínimos y las sólidamente fundada sobre una transmisión de conoci- competencias que deben adquirir los jóvenes al salir mientos muy estructurados, organizados en disciplinas del sistema educativo. escolares que se dedican la mayor parte a transmitir Este documento pretende averiguar cuáles son los conocimientos teóricos. La pedagogía es a menudo se- conocimientos y las competencias indispensables que cundaria, aunque los profesores disfrutan de una ver- deben dominar para terminar con éxito su escolaridad, dadera libertad pedagógica en sus clases. El trabajo seguir su formación y construir su futuro personal y crítico sobre los medios que estaba aún en elaboración profesional. Siete competencias diferentes han sido te- necesitaba este empuje para hacerse oficial. nidas en cuenta y en cada una de ellas, el trabajo con Aunque el trabajo de educación en los medios no los medios es reconocido frecuentemente. Para citar esté reconocido como disciplina, no está ausente de un ejemplo, la competencia sobre el dominio de la len- gua francesa definen las capa- cidades para expresarse oral- La metodología elaborada en el marco de la educación en mente que pueden adquirirse con la utilización de la radio e, medios parece incluso permitir la inclinación de la sociedad incluso, se propone fomentar de la información hacia una sociedad del conocimiento, como defiende la UNESCO. En Francia, se necesitaría unir el interés por la lectura a través de la lectura de la prensa. La educación en los medios las fuerzas dispersas en función de los soportes mediáticos y orientarse más hacia la educación en medios que al dominio adquiere pleno derecho y entidad en la sección sexta titulada «competencias sociales y cívi- técnico de los aparatos. cas» que indica que «los alum- nos deberán ser capaces de juz- gar y tendrán espíritu crítico, lo que supone ser educados en los las programaciones oficiales, ya que, a lo largo de un medios y tener conciencia de su lugar y de su influencia estudio de los textos, los documentalistas del CLEMI en la sociedad». han podido señalar más de una centena de referencias a la educación de los medios en el seno de disciplinas 4. Un entorno positivo como el francés, la historia, la geografía, las lenguas, Si nos atenemos a las cifras, el panorama de la las artes plásticas : trabajos sobre las portadas de educación en medios es muy positivo. Una gran ope- prensa, reflexiones sobre temas mediáticos, análisis de ración de visibilidad como la «Semana de la prensa y publicidad, análisis de imágenes desde todos los ángu- de los medios en la escuela», coordinada por el CLE- los, reflexión sobre las noticias en los países europeos, MI, confirma año tras año, después de 17 convocato- información y opinión rias, el atractivo que ejerce sobre los profesores y los Esta presencia se constata desde la escuela mater- alumnos. Concebida como una gran operación de nal (2 a 6 años) donde, por ejemplo, se le pregunta a complementariedad source of circulating FGF-21. The lack of association between circulating and muscle-expressed FGF-21 also suggests that muscle FGF-21 primarily works in a local manner regulating glucose metabolism in the muscle and/or signals to the adipose tissue in close contact to the muscle. Our study has some limitations. The number of subjects is small and some correlations could have been significant with greater statistical power. Another aspect is that protein levels of FGF-21 were not determined in the muscles extracts, consequently we cannot be sure the increase in FGF-21 mRNA is followed by increased protein expression. In conclusion, we show that FGF-21 mRNA is increased in skeletal muscle in HIV patients and that FGF-21 mRNA in muscle correlates to whole-body (primarily reflecting muscle) insulin resistance. These findings add to the evidence that FGF-21 is a myokine and that muscle FGF-21 might primarily work in an autocrine manner. Acknowledgments We thank the subjects for their participation in this study. Ruth Rousing, Hanne Willumsen, Carsten Nielsen and Flemming Jessen are thanked for excellent technical help. The Danish HIV-Cohort is thanked for providing us HIV-related data. 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