Samejima's Model Research Articles

Vocal Tract Discomfort Scale-Brazil (VTDS-BR): Validation Based on Internal Consistency, Reliability, and Accuracy

ObjectiveTo validate the Vocal Tract Discomfort Scale for the Brazilian Portuguese (VTDS-BR), based on internal consistency, reliability and accuracy. MethodsThe participants were 431 adults of both sexes, divided in two groups: dysphonia (DG) and vocally healthy (VHG). We built a digital database with personal, professional information and the item-by-item VTDS-BR responses of the participants. We applied Cronbach's alpha, exploratory factor analysis (EFA); confirmatory factor analysis (CFA); Item Response Theory (IRT) using the Samejima model; and ROC curve analysis to obtain the VTDS-BR cut-off point. ResultsThe VTDS-BR has an eight-item structure and two factors: vocal hyperfunction without phonotraumatic injury and with phonotraumatic injury. Each item is evaluated based on two facets related to frequency and intensity, with a Likert scale response key. There are four possible answers: never, sometimes, often, and always for frequency and none, mild, moderate, and intense for intensity. We applied an IRT model, which allowed the identification of which items are more related to dysphonia, based on higher values in the parameters discrimination (a) and difficulty (b), which contributed to the calculation of each participant's aptitude for the development of voice problems, by means of a score. The cut-off value was determined using the ROC curve, in which values greater than -1.432 indicate a higher probability of voice alterations. ConclusionVTDS-BR went through the stages of validation of internal consistency, reliability and accuracy. It presents an 8-item, two-factor, and two-facet structure to assess frequency and intensity of vocal tract discomfort symptoms. VTDS-BR is suitable for clinical use or in screening activities, as it is quick to apply and its interpretation is indicative of people with and without phonotraumatic injury.

Urica-VV Scale: A New Research Perspective of The Stage of Readiness for Treatment in Patients with Dysphonia

ObjectiveTo obtain evidence of validity for the URICA-V scale and estimate the psychometric properties of its items based on item response theory (IRT). MethodA total of 658 individuals of both sexes over 18 years of age were allocated into two groups: with dysphonia group (WDG) and vocally healthy group (VHG). A digital database was constructed with personal and professional data and item-by-item responses on the URICA-V scale. Subsequently, Cronbach's alpha, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), application of IRT using Samejima's model and ROC curve analysis were used to obtain the cutoff point for the URICA-V scale. ResultsA different version of the original URICA-V scale was obtained. Of the 32 items from the original protocol, 25 better explained the instrument and were regrouped into two domains: contemplation and maintenance. It was possible to identify which items generated higher difficulty (b) and discrimination (a) values and which contributed to the presentation of a calculation based on the theta of each participant. The ROC curve was analyzed, and a cutoff point of -0.236 was established; establishing a cutoff point facilitates the decision of which individuals are in a state of readiness for voice treatment. ConclusionThe present study provided evidence that allows us to propose the URICA-Voice validated (URICA-VV) scale within a more contemporary perspective and with a reduced number of items and domains. In addition, a cutoff point was obtained based on IRT to measure, with greater accuracy, sensitivity and specificity, the stage of readiness and to differentiate individuals who have an indication for speech therapy.

Underlying dimensions of the EORTC QLQ-C30 in a Cuban population of patients with advanced non-small cell lung cancer.

Quality of Life Core Questionnaire of the European Organization for the Research and Treatment of Cancer (EORTC QLQ-C30) is one of the most used quality of life questionnaires in cancer studies. It provides scores for five functional scales, nine symptom scales, and two single items which assess overall health status and quality of life. However, high correlations among QLQ-C30 items suggest a reduced dimensionality for the scale. To assess the dimensionality of the EORTC QLQ-C30 using item response theory (IRT) in a training sample and confirmatory factor analysis (CFA) in a test sample. We analyzed responses to QLQ-C30 from 1,107 patients with advanced lung cancer who were included in five clinical trials of immunotherapy. We used non-parametric and parametric IRT models (Mokken, and Samejima's graded response) in a random training set (n = 332) for initial assessment of dimensions and item characteristics of the QLQ-C30. Finally, we used CFA in the test set (n = 775) to confirm the measurement domains. Mokken model showed that QLQ-C30 fits a unidimensional scale, whereas Samejima model showed that most QLQ-C30 items present adequate difficulty and discrimination. All items showed adequate scalability indexes with an overall scalability of 0.47 (medium scale). The QLQ-C30-reduced dimensionality was confirmed by CFA (comparative fit index = 0.98, root mean square error of approximation = 0.055) with all items presenting factorial loadings > 0.40. The EORTC QLQ-C30 fits a unidimensional latent construct identified with perceived quality of life in advanced lung cancer patients. RPCEC00000161, RPCEC00000181 and RPCEC00000205.

Psychometric Properties of the SymptoMScreen Questionnaire in a Mild Disability Population of Patients with Relapsing-Remitting Multiple Sclerosis: Quantifying the Patient's Perspective.

Crucial elements for achieving optimal long-term outcomes in multiple sclerosis (MS) are patient confidence and effective physician–patient communication. Patient-reported instruments may provide the means to fill the gap in currently available clinician-rated measures. The SymptoMScreen (SMSS) is a brief self-assessment tool for measuring symptom severity in 12 neurologic domains commonly affected by MS. We conducted a non-interventional study to assess the dimensional structure and item characteristics of the SMSS. A total of 218 patients with relapsing–remitting MS and mild disability (median Expanded Disability Status Scale score 2.0) were studied. Symptom severity was low (SMSS score 13.5, interquartile range 4.2–27), fatigue being the domain with the highest impact. A non-parametric item response theory, i.e., Mokken analysis, found that the SMSS is a robust one-dimensional scale (overall scalability index H 0.60) with high reliability (Cronbach’s alpha 0.94). The confirmatory factor analysis model confirmed the unidimensional structure (comparative fit index 1.0, root-mean-square error of approximation 0.001). Samejima’s model fitted well an unconstrained model with different item difficulties. The SMSS shows appropriate psychometric characteristics and may constitute a valuable and easy-to-implement addition to measure the symptom severity in clinical practice.

Assessing fatigue in multiple sclerosis: Psychometric properties of the five-item Modified Fatigue Impact Scale (MFIS-5).

Fatigue in multiple sclerosis is a key symptom associated with work-related problems and poor quality of life outcomes. The five-item Modified Fatigue Impact Scale is a brief self-assessment tool for measuring the impact of fatigue on cognitive, physical and psychosocial function. A non-interventional, cross-sectional study was conducted to assess dimensionality and item characteristics of the five-item Modified Fatigue Impact Scale in multiple sclerosis. A total of 302 subjects were studied. Mokken analysis found the five-item Modified Fatigue Impact Scale is a strong one-dimensional scale (overall scalability index H = 0.67) with high reliability (Cronbach’s alpha = 0.90). The confirmatory factor analysis model confirmed the one-dimensional structure (comparative fit index = 1.0, root-mean-square error of approximation = 0.035). Samejima’s model fitted well as an unconstrained model with different item difficulties. The five-item Modified Fatigue Impact Scale shows appropriate psychometric characteristics and may constitute a valuable and easy-to-implement addition to measure the impact of fatigue in clinical practice.

Item response theory analysis applied to the Spanish version of the Personal Outcomes Scale.

The study of measurements of quality of life (QoL) is one of the great challenges of modern psychology and psychometric approaches. This issue has greater importance when examining QoL in populations that were historically treated on the basis of their deficiency, and recently, the focus has shifted to what each person values and desires in their life, as in cases of people with intellectual disability (ID). Many studies of QoL scales applied in this area have attempted to improve the validity and reliability of their components by incorporating various sources of information to achieve consistency in the data obtained. The adaptation of the Personal Outcomes Scale (POS) in Spanish has shown excellent psychometric attributes, and its administration has three sources of information: self-assessment, practitioner and family. The study of possible congruence or incongruence of observed distributions of each item between sources is therefore essential to ensure a correct interpretation of the measure. The aim of this paper was to analyse the observed distribution of items and dimensions from the three Spanish POS information sources cited earlier, using the item response theory. We studied a sample of 529 people with ID and their respective practitioners and family member, and in each case, we analysed items and factors using Samejima's model of polytomic ordinal scales. The results indicated an important number of items with differential effects regarding sources, and in some cases, they indicated significant differences in the distribution of items, factors and sources of information. As a result of this analysis, we must affirm that the administration of the POS, considering three sources of information, was adequate overall, but a correct interpretation of the results requires that it obtain much more information to consider, as well as some specific items in specific dimensions. The overall ratings, if these comments are considered, could result in bias.

Psychometrical assessment and item analysis of the General Health Questionnaire in victims of terrorism.

There is a need to assess the psychiatric morbidity that appears as a consequence of terrorist attacks. The General Health Questionnaire (GHQ) has been used to this end, but its psychometric properties have never been evaluated in a population affected by terrorism. A sample of 891 participants included 162 direct victims of terrorist attacks and 729 relatives of the victims. All participants were evaluated using the 28-item version of the GHQ (GHQ-28). We examined the reliability and external validity of scores on the scale using Cronbach's alpha and Pearson correlation with the State-Trait Anxiety Inventory (STAI), respectively. The factor structure of the scale was analyzed with varimax rotation. Samejima's (1969) graded response model was used to explore the item properties. The GHQ-28 scores showed good reliability and item-scale correlations. The factor analysis identified 3 factors: anxious-somatic symptoms, social dysfunction, and depression symptoms. All factors showed good correlation with the STAI. Before rotation, the first, second, and third factor explained 44.0%, 6.4%, and 5.0% of the variance, respectively. Varimax rotation redistributed the percentages of variance accounted for to 28.4%, 13.8%, and 13.2%, respectively. Items with the highest loadings in the first factor measured anxiety symptoms, whereas items with the highest loadings in the third factor measured suicide ideation. Samejima's model found that high scores in suicide-related items were associated with severe depression. The factor structure of the GHQ-28 found in this study underscores the preeminence of anxiety symptoms among victims of terrorism and their relatives. Item response analysis identified the most difficult and significant items for each factor.

Individual identification using personality traits

In this article, a pioneer study is conducted to evaluate the possibility of identifying people through their personality traits. The study is conducted using the answers of a population of 734 individuals to a collection of 206 items. These items aim at measuring five common different personality traits usually called the big five. These five levels are neuroticism, extraversion, agreeableness, conscientiousness and openness. The traits are estimated using the widely used Samejima's model and then used to discriminate the individuals. Results point biometrics using personality traits as a new promising biometric modality.

Further Empirical Results on Parametric Versus Non-Parametric IRT Modeling of Likert-Type Personality Data

Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in their data. To verify this conjecture, we compare the fit of these models to the Social Problem Solving Inventory-Revised, whose scales were designed to be unidimensional. A calibration and a cross-validation sample of new observations were used. We also included the following parametric models in the comparison: Bock's nominal model, Masters' partial credit model, and Thissen and Steinberg's extension of the latter. All models were estimated using full information maximum likelihood. We also included in the comparison a normal ogive model version of Samejima's model estimated using limited information estimation. We found that for all scales Samejima's model outperformed all other parametric IRT models in both samples, regardless of the estimation method employed. The non-parametric model outperformed all parametric models in the calibration sample. However, the graded model outperformed MFS in the cross-validation sample in some of the scales. We advocate employing the graded model estimated using limited information methods in modeling Likert-type data, as these methods are more versatile than full information methods to capture the multidimensionality that is generally present in personality data.

Validation of a questionnaire to evaluate the attitude towards primary prevention advice from the European code against cancer.

Educative interventions to promote primary prevention of cancer (PPC) should be based on psychosocial models and be tailored to attitude. Attitude is a difficult variable to measure. The aim of this study was to draw up a questionnaire to evaluate the attitude to PPC of relatives of patients affected by cancer. An interview of 48 patients, who answered open questions, allowed 67 items to be drawn up. Three hundred and fifty-five people answered the self-administered questionnaire of 67 items (69 of them did it twice, with an interval of 2 weeks). The factorial analysis revealed five factors that explain the 36% total and the 115% common estimated variance. The Cronbach's alpha oscillated between 0.80 and 0.93. The intraclass correlation coefficient was 0.7721 (95% CI (confidence interval) 0.6311-0.8592, P<0.0001). The analysis based on Samejima's model ordered the items according to their discriminating power and the difficulty/ease with which people agree with the most preventive option. The average scores obtained in both surveys of 69 people did not show significant statistical differences (P=0.195). The definitive questionnaire obtained has 63 items that measure attitude to PPC behaviour in a reliable and stable way.