Item Characteristic Curves Research Articles

Identifiability analysis of the fixed-effects one-parameter logistic positive exponent model.

In addition to the usual slope and location parameters included in a regular two-parameter logistic model (2PL), the logistic positive exponent (LPE) model incorporates an item parameter that leads to asymmetric item characteristic curves, which have recently been shown to be useful in some contexts. Although this model has been used in some empirical studies, an identifiability analysis (i.e., checking the (un)identified status of a model and searching for identifiablity restrictions to make an unidentified model identified) has not yet been established. In this paper, we formalize the unidentified status of a large class of fixed-effects item response theory models that includes the LPE model and related versions of it. In addition, we conduct an identifiability analysis of a particular version of the LPE model that is based on the fixed-effects one-parameter logistic model (1PL), which we call the 1PL-LPE model. The main result indicates that the 1PL-LPE model is not identifiable. Ways to make the 1PL-LPE useful in practice and how different strategies for identifiability analyses may affect other versions of the model are also discussed.

Harmonizing measurements: establishing a common metric via shared items across instruments

BackgroundThe proliferation of instruments that define instrument-specific metrics impedes progress in comparative assessment across populations. This paper explores a method to extract a common metric from related but different instruments and transform the original measurements into scores with a standard unit of measurement.MethodsExisting data from four assessment instruments of child development, collected from three different samples of children, were used to create “equate clusters” of items that measure the same behaviour in (slightly) different ways. A probability model was formulated to identify best items and groups to serve as anchors linking the instruments, assuming that items in an anchoring or “active” equate cluster are psychometrically equivalent. Quantification and inspection of item characteristic curves were used to resolve which equate clusters should be active. We simulated the impact of various analytic choices.ResultsSimulation confirmed the feasibility of creating a common metric from data collected with different instruments from respondent samples with different abilities. The method performed as expected in an application in early childhood development.ConclusionsThe use of equate clusters is an intuitive and flexible way to establish a common metric across instruments and facilitates the transformation of measurements obtained to a standardized scale. Standardizing instrument scores to a common metric allows for population-level comparisons on a global scale.

Using Item Response Theory to Develop a Shortened Version of the Penn State Worry Questionnaire for Children.

The PSWQ-C is a widely used international scale to measure worry traits in children and adolescents. It has been translated into several versions for use in different countries. The purpose of this study was to examine the psychometric characteristics of the Penn State Worry Questionnaire for Children (PSWQ-C) particularly three reverse-scored items, and to develop a shorter version of the PSWQ-C based on Item Response Theory (IRT) methods. 903 children and adolescents of different ages from China participated in the study. This study used the Graded Response Model (GRM) to fit the data and examined the IRT parameters of each item, Item Characteristic Curve, Item Information Functions, and Differential Item Functioning. Eight items with undesirable functioning were removed, while six items with good functioning were retained, resulting in a simplified version of the PSWQ-C. The abbreviated version of the PSWQ-C was subsequently validated for its reliability and validity. The results confirmed that the abbreviated scale is reliable and effective, with a Cronbach's alpha coefficient of 0.84, indicating good reliability. Regarding validity, the abbreviated version of the PSWQ-C demonstrated significant correlations with IUS-12 and MASC, both exceeding 0.60, which closely resembles the correlation of the original PSWQ-C with these two scales. Furthermore, the correlation between the two versions was 0.96, indicating that the abbreviated PSWQ-C can effectively replace the original version and has a broader range of applications.

Sport mental health continuum in young Brazilian athletes: adaptation and psychometric properties

Instruments used to assess the mental well-being of young athletes in Brazil are scarce. Therefore, the present study aimed to translate, cross-culturally adapt for young athletes, and gather evidence of validity for the Sport Mental Health—Short Form (S-MHC) for use in Brazilian Portuguese. The research was conducted in five stages: translation, synthesis, back-translation, expert review, and validation of the psychometric properties. For validation, 246 young athletes of both genders (88 females, 35.8%), aged between 12 and 18 years (14.5 ± 1.9 years), were recruited. Psychometric methods were employed to confirm and validate the translated and adapted versions of the S-MHC for young athletes, including internal consistency using Cronbach's alpha and McDonald's omega, composite reliability, Item Characteristic Curve (ICC) using Item Response Theory (IRT), and Confirmatory Factor Analysis (CFA). Two structures were tested, with Model 1 loading the 14 items of the translated version of the S-MHC into a single latent factor and Model 2 loading the items into three factors related to emotional, social, and psychological sport well-being. Both models showed good validity, consistency, and reliability measures and can be used to investigate the sport well-being of young athletes. It was concluded that the translated version of the S-MHC in Brazilian Portuguese can be used to assess the sport well-being of young athletes in Brazil. Model 2 structure is recommended to observe the different nuances of emotional, social, and psychological well-being.

Mokken scale analysis of the Internet Gaming Disorder Scale–Short-Form and the Gaming Disorder Test

In recent years, research on Gaming Disorder (GD) has grown substantially with researchers developing different psychometric tools for assessing disordered gaming. Two of the most prominent tools are the Internet Gaming Disorder Scale–Short-Form (IGDS9-SF) and the Gaming Disorder Test (GDT), which assess disordered gaming under the American Psychiatric Association (APA) and the World Health Organisation (WHO) frameworks respectively. The main aim of this study was to assess and compare the scalability, reliability, and validity of both scales to determine if the tools effectively assess GD in a normative sample, through the Mokken Scale Analysis (MSA). A sample of 605 participants (42.31 % female, meanage = 23.98 years, SD = 9.21 years) was recruited for the present study. Results showed that both the IGDS9-SF and GDT were unidimensional, with all items presenting latent monotonicity fitting in the Monotone Homogeneity Model (MHM). Item characteristic curves did not intersect and presented with adequate fit in the Double Monotonicity Model (DMM). These findings further support the psychometric adequacy of the IGDS9-SF and GDT, attesting to their suitability to assess disordered gaming.

The irtQ R package: a user-friendly tool for item response theorybased test data analysis and calibration.

Computerized adaptive testing (CAT) has become a widely adopted test design for high-stakes licensing and certification exams, particularly in the health professions in the United States, due to its ability to tailor test difficulty in real time, reducing testing time while providing precise ability estimates. A key component of CAT is item response theory (IRT), which facilitates the dynamic selection of items based on examinees' ability levels during a test. Accurate estimation of item and ability parameters is essential for successful CAT implementation, necessitating convenient and reliable software to ensure precise parameter estimation. This paper introduces the irtQ R package (http://CRAN.R-project.org/), which simplifies IRTbased analysis and item calibration under unidimensional IRT models. While it does not directly simulate CAT, it provides essential tools to support CAT development, including parameter estimation using marginal maximum likelihood estimation via the expectation-maximization algorithm, pretest item calibration through fixed item parameter calibration and fixed ability parameter calibration methods, and examinee ability estimation. The package also enables users to compute item and test characteristic curves and information functions necessary for evaluating the psychometric properties of a test. This paper illustrates the key features of the irtQ package through examples using simulated datasets, demonstrating its utility in IRT applications such as test data analysis and ability scoring. By providing a user-friendly environment for IRT analysis, irtQ significantly enhances the capacity for efficient adaptive testing research and operations. Finally, the paper highlights additional core functionalities of irtQ, emphasizing its broader applicability to the development and operation of IRT-based assessments.

Psychometric properties and diagnostic performance of three dry eye questionnaires in Italian: OSDI, OSDI-6, and SPEED.

Psychometric questionnaires are highly valuable instruments in clinical practice as they make subjective symptoms easier to measure. Recently, a short version of the Ocular Surface Disease Index (OSDI) questionnaire was developed, named OSDI-6. This study aimed to assess the psychometric properties and compare the diagnostic criteria of three questionnaires, available in the Italian language, designed for assessing dry eye disease: Standard Patient Evaluation of Eye Dryness (SPEED), OSDI-12, and specifically the new shortened version, OSDI-6. Psychometric evaluations were conducted on 250 adult participants aged 20 to 83 years. Classic and Rasch psychometric analyses were performed on the three questionnaires. The repeatability of the questionnaires was assessed by retesting 120 participants. The exploratory factor analysis of OSDI-6 indicated saturation on two factors. Repeatability was optimal for all three questionnaires. Based on the reference OSDI-12, the cutoff for OSDI-6 was 5 points and 7 for SPEED. Rasch analysis showed that OSDI-6 and OSDI-12 present disordered response categories and thresholds. Conversely, the SPEED questionnaire shows the optimal item characteristic curve. The OSDI-12 is a reference questionnaire used in dry eye disease studies and clinics, but OSDI-6 does not represent a perfect shortened version, primarily for the absence of one factor measured and secondarily for the same problem of category response order and thresholds. Conversely, SPEED focusing only on symptoms showed better psychometric properties.

Assessing health-related quality of life using the Wound-QoL-17 and the Wound-QoL-14-Results of the cross-sectional European HAQOL study using item response theory.

For assessing health-related quality of life in patients with chronic wounds, the Wound-QoL questionnaire has been developed. Two different versions exist: the Wound-QoL-17 and the Wound-QoL-14. For international and cross-cultural comparisons, it is necessary to demonstrate psychometric properties in an international study. Therefore, the aim of this study was to test both questionnaires in a European sample, using item response theory (IRT). Participants were recruited in eight European countries. Item characteristic curves (ICC), item information curves (IIC) and differential item functioning (DIF) were calculated. In both questionnaires, ICCs for most items were well-ordered and sufficiently distinct. For items, in which adjacent response categories were not sufficiently distinct, response options were merged. IICs showed that items on sleep and on pain, on worries as well as on day-to-day and leisure activities had considerably high informational value. In the Wound-QoL-14, the item on social activities showed DIFs regarding the country and age. The same applied for the Wound-QoL-17, in which also the item on stairs showed DIFs regarding age. Our study showed comparable results across both versions of the Wound-QoL. We established a new scoring method, which could be applied in international research projects. For clinical practice, the original scoring can be maintained.

Item and Test Characteristic Curves of Rank-2PL Models for Multidimensional Forced-Choice Questionnaires

ABSTRACT A process is proposed to create the one-dimensional expected item characteristic curve (ICC) and test characteristic curve (TCC) for each trait in multidimensional forced-choice questionnaires based on the Rank-2PL (two-parameter logistic) item response theory models for forced-choice items with two or three statements. Some examples of ICC and TCC plots from a real pair form and triplet form are provided, and they appear to help identify misfit trait scores at the item and test levels. TCC plots with negative statements changed to positive ones are also proposed.

Psychometric properties of the health literacy instrument in Brazil (HLS-EU-BR47)

BackgroundHealth literacy (HL) is a key component of health promotion and sustainability and contributes to well-being. Despite its global relevance, HL is an under-researched topic in South America but is now debuting its exploration in Brazil. To leverage its benefits for South America, the mere translation of validated tools into Portuguese is insufficient. Rather, it is necessary to examine their validity. This study aims to assess the psychometric properties of the European Health Literacy Questionnaire (HLS-EU-BR47) using the Item Response Theory (IRT) in a population-based sample of adults in Brazil.MethodsA cross-sectional online study was conducted across Brazil and included 1028 participants aged 18 years and above (80% women). Cronbach’s alpha, McDonald’s omega, factor analysis, graded responses model, Item Characteristic Curve, HL levels based on this, HL standard calculation, IRT, and regular score correlation were computed.ResultsThe instrument exhibit high reliability (Cronbach’s alpha 0.95). Factor analysis yielded one factor. IRT was appropriate for data analysis because it allowed quality evaluation of items and constructed a scale to quantify HL. The 47 items and latent features of respondents in the same unit of measurement are positioned in the construction of the HLS-EU-BR47 instrument. The percentages of individuals at each HL level, calculated using IRT, were found to be comparable to those obtained through the standard computation, e.g., 3.2% of people reported very low HL versus 10.8% inadequate HL, 56.2% reported low HL versus 39.5% problematic HL, 31.1% had moderate HL versus 30.1% sufficient HL, and 9.5% had high HL versus 19.7% with excellent HL. The mean HL scores were comparable between women and men (33.9 vs. 33.7, P = 0.36).ConclusionThis study provides new evidence of the validity of a widely used HL instrument for the population of South America (in this case, Brazil). This tool can be utilized by citizens, health professionals, and regional/national policymakers to inform the development of initiatives to assess and improve the HL of individuals, groups, and communities. Further studies are needed to confirm and extend the findings and to explore the influence of local cultures and practices in the vast Brazilian territory on HL.

Initial evaluation of measurement properties of the Work Environment Impact Questionnaire (WEIQ) - using Rasch analysis

BackgroundTo provide both preventive and rehabilitative conditions in a workplace, one must understand how employees experience work demands. Such an understanding can be obtained from each individual with valid and quality-assured questionnaires. The Work Environment Impact Questionnaire (WEIQ) is a new questionnaire for measuring employees’ self-perceived work ability in relation to their specific workplace environment. The purpose of this study was to assess the measurement properties in terms of construct validity of the WEIQ.MethodsA cross-sectional survey study was conducted with 288 respondents from three different workplaces involving assisted living personnel, vocational rehabilitation personnel and personnel at a research institute. The measurement properties of the WEIQ were assessed according to Rasch Measurement Theory (RMT), including assessment of item-to-sample targeting, threshold ordering, item fit statistics, unidimensionality and reliability.ResultsItem fit, i.e., fit residuals, item characteristic curves (ICC) and chi square values, were all satisfactory, and no disordered thresholds were present after collapsing the lowest response categories. However, issues with local dependent (LD) item correlations was present in 7.6% cases, four items showed statistically significant differential item functioning (DIF), where 11% of the respondents had person fit residuals outside the recommended range of ± 2.5 and the t-test for unidimensionality did not meet the criterion of 5%. Scale-to-sample targeting and reliability (0.92) were good. LD could be resolved with testlets and at the same time maintaining fit and improving dimensionality, but then the reliability decreased to 0.82.ConclusionsThis study provides an initial validation of the WEIQ to be used for assessing employees’ self-perceived work ability. Most measurement properties were acceptable, but further exploration of LD, DIF and unidimensionality in additional work settings and with larger sample sizes is warranted.Trial registrationNot applicable.

Medical Student's Knowledge and Perspective Regarding Organ Donation In Punjab.

Objectives: This study aimed to evaluate the knowledge, attitudes, and practices of organ donation among undergraduate medical students and explore potential variations based on demographic characteristics. Methodology: A Cross-Sectional Study was conducted from June to September 2023; participants were recruited from Punjab medical, dental, and paramedic colleges. Data was gathered using a structured questionnaire, which was pre-tested prior to the study. The online data collected was analyzed using SPSS version 28. Qualitative variables were reported in frequencies and percentages, and the Chi-square test assessed associations among study variables and sociodemographic traits. Results: The study enrolled 152 students, predominantly from the MBBS program (80%). Inconsistencies were observed in knowledge, attitude, and practice domains. Approximately 55.6% of students were aware of organ donation, while only 45.5% exhibited a positive attitude, particularly in donating under exceptional circumstances. The group below 18 years demonstrated a high percentage (45.5%) of willingness to become organ donors. Notably, a significant portion of participants expressed comfort and positive feelings about posthumous organ donation. Conclusion: The data revealed various perspectives and challenges associated with organ donation. Some participants mentioned issues like religious constraints, family opposition, and concerns about physical appearance or mortality. Moreover, a variety of "Other" barriers were identified, indicating a wide range of reservations. Nevertheless, the majority clearly grasped the selfless intent behind organ donation, with the main drive being to preserve and prolong human life. The results highlight the necessity for continuous efforts to enhance awareness, educate the public, and address reservations in order to encourage organ donation and ultimately save lives. Keywords: Organ donor, Organ recipient, Undergraduate Medical Students. Item characteristic curve.

Learner Competence Across Cognitive Levels In Undergraduate Medical Education: An Item Response Approach.

Objective: The current study endeavors to evaluate competence of learners using item response theory approach in undergraduate medical education. Methodology: The responses of the examinees from first professional year (MBBS) were evaluated for Anatomy discipline to gauge learner competence through knowledge, understanding and application in the subject using item response theory approach (IRT) which is an effective tool to measure the validity (discrimination and difficulty index) of assessment, while KR-20 is used to gauge reliability of the items with statistical software STATA 17. The quality of question and level of examinee responses provide skill level and competence of learners. Results: The current study found that the C1 and C3 level items from the Anatomy discipline are mostly acceptable and effectively gauge learner competence while flawed C2 level items need complete restructuring. The study also identified weak areas of average learner for items in each cognitive level. Conclusion: The study found significant role of IRT in effectively estimating competence of the examinees across cognitive levels for each discipline and in building of an effective test pool through assessment of learner ability and construction of quality SBAs to achieve valid and reliable assessment tool. Keywords: Difficulty index; Discrimination index; Single best answer questions; Cognitive levels; Item characteristic curve.

Development and validation of the Dermatology Social Comparison (DSC) Scale.

Social comparison, the process of evaluating one's characteristics in relation to others, influences individuals' self-perception and behavior. However, instruments are scarce for assessing social comparison in the medical setting. Our aim was to develop and validate a new scale for assessing social comparison. Seven statements were developed, encompassing the perceived normality of having rashes, the tendency to compare their situation with others, and the emotional response when seeing someone better or worse off than themselves. The instrument was piloted in 15 patients for readability and face validity, then prospectively validated using modern psychometric methods in 1,053 adult patients with eczema or psoriasis from three tertiary dermatological centers in Singapore. Of 1,053 adult patients, 802 (76.2%) had eczema, and 251 (23.8%) had psoriasis. Exploratory factor analysis (using a 70% sample split) showed a single factor model comprising three questions (Eigenvalue: 1.4). Confirmatory factor analysis with the remaining 30% of the sample confirmed an excellent model fit. Cronbach's alpha was 0.7, and inter-item correlations ranged from 0.42 to 0.46. In the Rasch analysis, item fit statistics and item characteristic curves showed appropriate discrimination between response options, although reliability was suboptimal with a person separation reliability of 0.63. Comprising 3 questions, the newly derived social comparison scale showed acceptable psychometrics as a measure of social comparison for clinical and research purposes in dermatology. Its brief nature likely results from its brevity and applicability to conditions beyond eczema and psoriasis, which warrants further investigation.

Development of a rapid tool for screening financial toxicity based on the comprehensive score for financial toxicity

ObjectiveThis study aimed to use item response theory (IRT) to develop and validate a short version of the Chinese COmprehensive Score for financial Toxicity (COST-S-C) in patients with cancer. MethodsA total of 500 patients with cancer participated in the survey. Confirmatory factor analysis (CFA) was used to assess the factor structure of the COST-S-C. A two-parameter IRT model was used to examine the item fit of the COST-S-C. Item discrimination, item characteristic curves (ICCs), item information curves (IICs), and item fit were estimated. Differential item functioning (DIF) was assessed for participants’ gender and age. Reliability, convergent and discriminant validity was examined as well as estimating the optimal cut-off points of the COST-S-C. ResultsThe CFA results supported the bi-factor structure of the COST-S-C. The IRT analysis findings revealed that several items showed problems with the ICCs, providing little information in terms of IICs as well as poor discrimination. Item 5 showed a negligible DIF problem with age. A valid 3-item COST-S-C scale and its optimal cut-off point was developed. ConclusionsThe COST-S-C is a valid and quick screening tool used to distinguish patients with cancer who report significant financial toxicity in various medical settings.

Linking Methods for Multidimensional Forced Choice Tests Using the Multi-Unidimensional Pairwise Preference Model.

Applications of multidimensional forced choice (MFC) testing have increased considerably over the last 20years. Yet there has been little, if any, research on methods for linking the parameter estimates from different samples. This research addressed that important need by extending four widely used methods for unidimensional linking and comparing the efficacy of new estimation algorithms for MFC linking coefficients based on the Multi-Unidimensional Pairwise Preference model (MUPP). More specifically, we compared the efficacy of multidimensional test characteristic curve (TCC), item characteristic curve (ICC; Haebara, 1980), mean/mean (M/M), and mean/sigma (M/S) methods in a Monte Carlo study that also manipulated test length, test dimensionality, sample size, percentage of anchor items, and linking scenarios. Results indicated that the ICC method outperformed the M/M method, which was better than the M/S method, with the TCC method being the least effective. However, as the number of items "per dimension" and the percentage of anchor items increased, the differences between the ICC, M/M, and M/S methods decreased. Study implications and practical recommendations for MUPP linking, as well as limitations, are discussed.

The development and evaluation of a scale to assess job satisfaction in public universities with item response theory: a Brazilian study

PurposeThis study aimed to develop a psychometrically reliable job satisfaction (JS) measure for university employees, guiding administrative decisions and monitoring satisfaction over time in public universities.Design/methodology/approachA JS survey developed by a Brazilian federal university’s sustainability committee containing 58 items across physical, cognitive and organizational domains was longitudinally tested with 1,214 responses collected. The data were analyzed using Item Response Theory (IRT) analysis, employing the Graded Response Model, with tools such as frequency analysis, item characteristic curve, and full-information factor analysis in RStudio. The scale’s criterion validity was also established via expert qualitative interpretation.FindingsThe instrument’s internal consistency was confirmed as the results demonstrated its high reliability with a marginal reliability coefficient of 0.95. Significant findings revealed that recognition and supervisor relationships were key discriminators of JS and that workers began to perceive satisfaction when basic environmental conditions were met.Research limitations/implicationsIt is important to mention that the application of this scale is specifically limited to higher education institutions and may not be directly applicable to other educational settings or industry sectors without modifications.Originality/valueAlthough numerous measures and scales have been developed to assess JS, one elaborated by using IRT in a public university environment was lacking. Due to shifting dynamics in the workplace, traditional measurement of JS has proven inadequate, necessitating a more precise, accessible and updated tool. The developed scale allows precisely targeted interventions to improve JS and can be reapplied to evaluate their effectiveness. This research thus contributes a valuable tool for academic organizational psychology, enhancing the understanding of the measurement of JS.

Assessing Measurement Invariance in ASWB Exams: Regulatory Research Proposal to Advance Equity

ABSTRACT Purpose Social workers from minoritized racial, ethnic, linguistic, and age groups are far less likely to pass licensing examinations required to practice. Using a simulated data set, our study investigates measurement equivalence, or invariance, of social work licensing exams. Materials For this analysis, we simulated responses to 15 multiple-choice questions which were scored as either correct or incorrect using the R mirt package and used mirt to fit a 2-parameter logistic model (2PL) to the response data. We generated the data so that five items could demonstrate DIF and calculated their impact on the test characteristic curves and item characteristic curves. Results Small amounts of differential item functioning added up into differential test functioning, but the effect size was small. This result is one potential outcome of an analysis of ASWB exams. Discussion Most studies evaluating test characteristic curves demonstrate small effect sizes. Measuring the test characteristic curve and the test information curve will help to investigate content-irrelevant sources of variance in the exams, including unfairness, unreliability, and invalid pass scores. Conclusion Differential test functioning is a core part of measurement invariance studies. Psychometric standards require test developers to assess measurement invariance at both the item-level and test-level to protect themselves from accusations of bias.

Psychometric Properties of the Persian Translation of the 12-Item Utah Photophobia Symptom Impact Scale Questionnaire

ABSTRACT To translate the the Utah Photophobia Symptom Impact Scale-12 questionnaire into Persian and assess the psychometric aspects to check its validity and reliability based on the Rasch modelling method. Translation and cultural adjustment of the English language UPSIS-12 questionnaire to Persian was undertaken. A total of 61 patients with complaints of photophobia participated in evaluating validity and reliability aspects. All the participants were asked to complete the Persian translation of the UPSIS-12 questionnaire. Rasch analyses of the survey items were conducted using WINSTEPS. All items fit the Rasch model. Point-measure correlation values varied from 0.41 to 0.77, providing a preliminary indication of adequate construct validity. All factor loadings were found more than 0.4. All items obtained infit and outfit mean square (MnSq) values of < 2.0. All participants except 5 had normal outfit values. Patients’ abilities relative to the items’ difficulty were analysed. Item difficulty was estimated and item characteristic curves were included. Sufficient unidimensionality, hierarchical order, and equal interval scoring were obtained. In conclusion, the Persian UPSIS-10 questionnaire has excellent psychometric properties and it will be valuable in both clinical practice and research. It will help Persian practitioners to assess their patients’ photophobia.

Revalidating a measurement instrument of spatial thinking ability for junior and high school students

Spatial thinking is a set of cognitive abilities that enable people to organize, reason about, and mentally manipulate both real and imagined spaces. One of the available measurement instruments is the Spatial Thinking Ability Test (STAT). Given the critical need for spatial thinking ability measurement for junior and high school students, and the popularity of STAT to measure spatial thinking ability, revalidation of STAT is necessary as STAT was developed primarily for university students and validation of the original STAT was based on the classical test theory from which the findings are notoriously sample dependent. We used Rasch modeling to revalidate STAT as it allows parameters to be mutually independent and measures to be interval. The sample included 1340 junior and high school students. Item fit statistics, Item Characteristics Curves, unidimensionality test, and the Wright map provided evidence for the construct validity of STAT measures. The reliability of the instrument was moderate. Wald test for item measure invariance of individual items showed that among sixteen items seven items were variant in measures. The Anderson LR test indicates that the Rasch difficulty measures of STAT were not adequate for invariance. There was no DIF between two subsamples based on gender, suggesting fairness of the instrument in terms of gender. The above results suggest that STAT possesses certain degrees of validity, reliability, and fairness, although there is still room for further improvement.