Classical Test Theory Research Articles

Establishing the measurement precision of the patient health questionnaire in an adolescent sample

BackgroundTechnically sound measures are necessary for accurately identifying youth at risk for depression, but many studies rely on classical test theory metrics or adult samples to evaluate measures. This study examined the use of the PHQ-8, a common and freely available pediatric depression screener, in an adolescent sample using item response theory (IRT). MethodsSecondary analyses were conducted on data from a study conducted in Midwestern middle schools in which 1224 youth completed the PHQ-8 as part of a battery of surveys. Polytomous IRT analyses (a Graded Response Model) were used to evaluate the PHQ-8. Items were examined for their ability to distinguish between respondents of different latent depression severity and for differential item functioning (DIF) across demographic categories. ResultsAll PHQ-8 items had adequate discriminative abilities. Items measuring anhedonia and psychomotor disturbances performed relatively poorly, and items measuring somatic symptoms (appetite and sleep) were most informative when respondents endorsed extreme response options (“not at all” or “nearly every day”). No DIF was found across grade level or race, but several items were flagged for DIF by gender and student income level. LimitationsThese results might not be generalizable to a broader youth population due to administration setting and the unique demographic characteristics of this sample (76.0 % African American). ConclusionsTools such as the PHQ-8 are appropriate to quickly screen for depression in adolescents, but further scrutiny of adolescent response patterns is warranted. Future research should examine items measuring anhedonia and psychomotor and somatic disturbances in adolescents.

Supplemental Material for What’s in a Score: A Longitudinal Investigation of Scores Based on Item Response Theory and Classical Test Theory for the Amsterdam Instrumental Activities of Daily Living Questionnaire in Cognitively Normal and Impaired Older Adults

Supplemental Material for What’s in a Score: A Longitudinal Investigation of Scores Based on Item Response Theory and Classical Test Theory for the Amsterdam Instrumental Activities of Daily Living Questionnaire in Cognitively Normal and Impaired Older Adults

Rasch Analysis of the Korean Version of the Tinnitus Handicap Inventory.

Tinnitus is the perception of abnormal sounds in the ears or head without external auditory stimulation. While classical test theory is often used in tinnitus questionnaire development, it has limitations in assessing item characteristics. Item response theory (IRT) offers more precise individual ability estimations and identifies key and less important items, making it superior for reliable measurement tools. This study investigated the suitability of the Korean version of the Tinnitus Handicap Inventory (K-THI) as a patient-reported outcome measure (PROM) for clinical trials. Using Rasch analysis based on IRT, we evaluated K-THI's measurement of tinnitus-related disability in 545 patients (40.4% men, 59.6% women). Five items (2, 7, 8, 19, and 24) did not fit the Rasch model, yet a unidimensional scale and good fit for person and item data emerged (person: 0.89; item: 0.98). The three-point rating scale in K-THI proved suitable. IRT allowed precise evaluation of K-THI's properties, vital for reliable PROMs in patient-centered care. Our findings highlight IRT's role in questionnaire development, contributing to the advancement of PROMs.

A complementary approach to measure construct validity of WHO QOL BREF in Indian multidrug-resistant tuberculosis (MDR-TB) patients through psychometric property and factor analysis

Background: Multidrug-resistant tuberculosis (MDR TB) affects the physical, psychosocial and inter-relationship structure and thus quality of life (QoL) of an individual. WHO QOL BREF is presumed to capture the QoL construct. This study investigates the diagnostic accuracy and construct of WHO QOL BREF from a psychometric perspective and complements and converges findings through classical test theory. Methods: The instrument validity study was conducted in a district of Central India amongst the microbiologically confirmed MDR TB cohort of year 2017 (n=98). We calculated global and domain-specific Cronbach alpha and Inter-domain Pearson correlations. The dichotomized items were fitted through Rasch model for item endorsement, response pattern and for variation inconsistencies. Item Characteristic Curves and person item maps were also plotted. We performed DIF (Differential Item Functioning) to check the effect of subgroups on underlying traits. This was complimented with an Exploratory Factor Analysis (EFA) using oblique ProMax rotation. The optimum number of factors were identified by Scree plot and parallel analysis approach and the emerging factor structure was compared with the result obtained through the Rasch model. Results: The global Cronbach’s alpha was 0.94 (95% CI 0.92-0.96). Social relationship domain had poor correlations with all three domains (r=0.42, r=0.41 r=0.58), higher beta values and less discrimination. DIF showed a differential response by gender. There was a visual clustering and a non-uniform distribution of items across the perceived QoL. A 3-factor model emerged through EFA and was reframed on the notion of self-concept. Items related to pain, medical aid had significant misfit and weak factor loading while items of sexual activity and social support had relatively poor performance in Infit, Wald, DIF on factor loading parameters. Conclusions: The study indicates the possible deviation of scale from theorized dimensional construct in Indian MDR TB context more with the items of the social relationship domain.

A Comparison of Covariates, Equating Designs, and Methods in Equating TIMSS 2019 Science Tests

This research aimed to compare the equated scores by the methods based on classical test theory (CTT) and kernel equating, using covariates design (NEC) and anchor test design (NEAT). TIMSS 2019 science test scores equated by both Tucker, Levine true score, Levine observed score, equipercentile equating (pre-smoothing and post-smoothing) methods in CTT, and linear and equipercentile methods in kernel equating. Additionally, the covariates in NEC design were “home resources for learning,” “student confidence in science and mathematics,” “like learning science,” “instructional clarity in science lessons,” “math achievement,” “sex,” and “speaking the language of the test at home”. The equating results in NEC were compared with those in NEAT and EG. The participants comprised 1699 4th-grade students who attended the e-TIMSS 2019 in Canada, Singapore, and Chile. Results were analyzed according to equating errors and differences between equated scores. The research concluded that math achievement and home resources for learning could be used as covariates in NEC to equate the science test in case equating could not be done in the NEAT. However, when the other variables were used as covariates in NEC, the equated scores were very similar to the EG. Also, Tucker (CTT) and post-stratification (kernel) yielded similar equated scores in linear equating, and these methods were similarly different from kernel linear equating in EG. In equipercentile equating, the equated scores obtained from the post-smoothing (CTT) and EG were close to each other but slightly differed from post-stratification.

Further Validation of the Social Efficacy and Social Outcome Expectations Scale

The current study sought out to advance the Social Self-Efficacy and Social Outcome Expectations scale using multiple approaches to scale development. Data from 583 undergraduate students were used in two scale development approaches: Classic Test Theory (CTT) and Item Response Theory (IRT). Confirmatory factor analysis suggested a 2-factor structure that aligns with the theoretically based domains for SEOES items and supports previously proposed models of this scale from CTT and psychometric analyses. The IRT analysis indicated that the SEOES items have greater measurement precision at measuring lower levels of the latent constructs. Future research directions are provided and practice implications are discussed.

The Science of Psychiatric Measurement

In this article, we compare and contrast mental health measurement based on classical test theory (CTT) with computerized adaptive testing (CAT) based on multidimensional item response theory (MIRT). We show that MIRT-based CAT has numerous advantages over the traditional CTT approach in terms of maximizing the precision of measurement while at the same time decreasing the burden of measurement both for the clinician and patient. We review the literature on CAT for depression, anxiety, mania/hypomania, posttraumatic stress disorder, suicidality psychosis, and substance use disorders. We highlight two interesting applications, one for national prevalence determination, and one for student mental health. Applications to special populations where item-level bias may exist and integration with electronic medical records systems are also discussed. [ Psychiatr Ann . 2023;53(9):400–404.]

The organizational trauma resilience assessment: Methods and psychometric properties.

Despite many strengths of trauma-informed care (TIC), critics argue TIC is necessary but alone insufficient, can be deficit focused, lacks construct operationalization, and requires greater inclusion of resilience theory. We sought to address these critiques by creating an assessment tool through an iterative and community-engaged process. We collected cross-sectional data between May and June 2019 with a convenience sample from 12 sites across the United States (N = 861). Data were analyzed through application of classical test theory and item response theory, using principal components analysis. The final 40-item Organizational Trauma Resilience Assessment (OTRA) is sufficiently unidimensional and has a five-factor solution with strong validity and reliability. We believe this instrument marks the first of its kind to synthesize tenets of organizational resilience with TIC principles. Creation of the OTRA progresses the TIC knowledge base and is a cost-effective and valid method for evaluating organizational culture of trauma resilience. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Examining the Psychometric Properties of the Career Commitment Instrument through Classical Test Theory and the Graded Response Model

The gaps that exist in the literature by conducting a comprehensive evaluation of the psychometric properties of the Career Commitment Instrument using CTT and GRM. This exploratory study aims to analyze the psychometric properties of the career commitment instrument using a classical test theory approach and graded response model. Research using cross-sectional design. Data were obtained from a career commitment questionnaire with 12 statement items and 250 respondents who were randomly selected. The summed ranking method (Likert) was used for scaling, with five response options. Data were analyzed using R Studio's traditional Graded Response Model Theory Test technique. Based on the findings, the quality of the career commitment instrument has an estimated reliability of 0.77 (reliable) and a standard measurement error of 3.3. This instrument has a good Endorsement Index and Discrimination Index, with a classic and modern approach. Furthermore, analysis of the stratified response model revealed that 10 items were suitable and 2 were not. If given to respondents with a low level of ability (θ=-2) to a high level of ability (θ=2), this instrument provides complete information of 58.93 with a standard error of 1.0. This instrument can be used by companies to assess the career commitment of their employees. Future research can test the convergent and divergent validity of the career commitment instrument with similar instruments or with different instruments, to strengthen its validity.

Further development and evaluation of a questionnaire targeting person-centred outpatient care for persons with long-term conditions

AimTo further develop the Person-Centred Care instrument for outpatient care (PCCoc), evaluate its user-friendliness and content validity, and to explore its basic psychometric properties in various outpatient settings for adults with long-term conditions.BackgroundPerson-centred care (PCC) has been identified as a key factor to provide high-quality care. However, there is still a lack of instruments that are based on a clearly defined framework for PCC for persons with long-term conditions in an outpatient context. The PCCoc is a patient-reported experience measure under development aiming to fill this gap.MethodsFirst, the 35-item PCCoc was reviewed and further developed in collaboration with a user-council. Second, the revised 36-item PCCoc was tested among persons receiving outpatient care for various long-term conditions. A total of 179 persons with long-term conditions from four different specialties participated in the study. User-friendliness and content validity were assessed through structured interviews and relevance ratings of each item. Content validity index (CVI) for individual items (I-CVI) and for the overall scale (S-CVI) were calculated, and basic psychometric properties of the PCCoc using classical test theory were explored.ResultsIt took a median of 8 min for participants to complete the PCCoc. The majority found items easy to understand, response categories distinct and that no important areas were missing. Results from the CVI analyses suggested that participants found the content of the PCCoc relevant (I-CVI range 0.82-1, S-CVI = 0.95). All psychometric properties examined were satisfactory (e.g., item-total correlations, 0.45–0.75; Cronbach’s alpha, 0.96; test-retest stability, 0.83).ConclusionThe PCCoc was considered user-friendly and relevant by the intended users, and its psychometric properties were satisfactory. This implies that the PCCoc can be a valuable instrument for evaluating and developing PCC in outpatient care for persons with long-term conditions. However, further studies of the PCCoc are needed to establish its measurement properties in various outpatient settings.

The Pain Anxiety Symptom Scale: Initial Development and Evaluation of 4 and 8 Item Short Forms

Elevated levels of anxiety in relation to chronic pain have been consistently associated with greater distress and disability. Thus, accurate measurement of pain-related anxiety is an important requirement in modern pain services. The Pain Anxiety Symptom Scale (PASS) was introduced over 30 years ago, with a shortened 20-item version introduced 10 years later. Both versions of the PASS were derived using Principal Components Analysis, an established method of measure development with roots in classical test theory. Item Response Theory (IRT) is a complementary approach to measure development that can reduce the number of items needed and maximize item utility with minimal loss of statistical and clinical information. The present study used IRT to shorten the 20-item PASS (PASS-20) in a large sample of people with chronic pain (N = 2,669). Two shortened versions were evaluated, 1 composed of the single best-performing item from each of its 4 subscales (PASS-4) and the other with the 2 best-performing items from each subscale (PASS-8). Several supplementary analyses were performed, including comparative item convergence evaluations based on sample characteristics (ie, female or male sex; clinical or online sample), factor invariance testing, and criterion validity evaluation of the 4, 8, and 20-item versions of the PASS in hierarchical regression models predicting pain-related distress and interference. Overall, both shortened PASS versions performed adequately across these supplemental tests, although the PASS-4 had more consistent item convergence between samples, stronger evidence for factor invariance, and accounted for 83% of the variance accounted for by the PASS-20% and 92% of the variance accounted for by the PASS-8 in criterion variables. Consequently, the PASS-4 is recommended for use in situations where a briefer evaluation of pain-related anxiety is appropriate. PerspectiveThe Pain Anxiety Symptom Scale (PASS) is an established measure of pain-related fear. This study derived 4 and 8-item versions of the PASS using IRT. Both versions showed strong psychometric properties, stability of factor structure, and relation to important aspects of pain-related functioning.

Psychometric properties career of commitment instrument using classical test theory and graded response model

Psychometric properties career of commitment instrument using classical test theory and graded response model

Modification and validation of the COVID-19 stigma instrument in nurses: A cross-sectional survey.

Nurses taking care of patients with infectious diseases have suffered from noticeable societal stigma, however currently, there is no validated scale to measure such stigma. This study aimed to revise and validate the COVID-19 Stigma Instrument-Nurse-Version 3 (CSI-N-3) by using item response theory (IRT) as well as classical test theory analysis. In phase I, the Chinese CSI-N-3 was modified from the English version of HIV/AIDS Stigma Instrument-Nurse based on standard cross-cultural procedures, including modifications, translation/back translations, pilot testing, and psychometric testing with classical test theory and Rasch analysis. In phase II, a cross-sectional study using cluster sampling was conducted among 249 eligible nurses who worked in a COVID-19-designed hospital in Shanghai, China. The influencing factors of COVID-19-associated stigma were analyzed through regression analysis. In phase I, the two-factor structure was verified by confirmatory factor analysis, which indicated a good model fit. The 15-item CSI-N-3 achieved Cronbach's α of 0.71-0.84, and composite reliability of 0.83-0.91. The concurrent validity was established by significant association with self-reported physical, psychological, and social support levels (r = -0.18, -0.20, and -0.21, p < 0.01). In IRT analysis, the CSI-N-3 has ordered response thresholds, with the Item Reliability and Separation Index of 0.95 and 4.15, respectively, and the Person Reliability and Separation Index of 0.20 and 0.50, respectively. The infit and outfit mean squares for each item ranged from 0.39 to 1.57. In phase II, the mean score for the CSI-N-3 in Chinese nurses was 2.80 ± 3.73. Regression analysis showed that social support was the only factor affecting nurses' COVID-19-associated stigma (standardized coefficients β = -0.21, 95% confidence interval: -0.73 ~ -0.19). The instrument CSI-N-3 is equipped with rigorous psychometric properties that can be used to measure COVID-19-associated stigma during and after the COVID-19 pandemic among nurses. The use of this instrument may facilitate the evaluation of tailored stigma-reduction interventions.

Psychometric Results of a New Patient-Reported Outcome Measure for Uveal Melanoma Post-Brachytherapy Treatment: The PROM-UM.

The objective of this study was to evaluate the psychometric properties of a new patient-reported outcome instrument intended for use with patients who have undergone brachytherapy for uveal melanoma (PROM-UM). Classical test theory and item response theory were used to evaluate the performance of individual items and domains. A convenience sample of 439 participants who had undergone brachytherapy for uveal melanoma from one of three North American ocular oncology treatment centers were included in this cross-sectional study. Exploratory factor analysis identified three domains which were labelled "Symptom Impairment", "Worry", and "Discomfort". The acceptability of the instrument was supported by little missing data (range = 0.00-1.14%) and low maximum endorsement (range = 0.00-1.82%). Item-total (range = 0.68-0.85) and inter-item (range = 0.74-0.80) correlations indicated acceptable reliability. Discrimination and difficulty were assessed using item response theory. Items in all three domains indicated moderate to very high discrimination (range = 1.00-4.10). Two items in the Symptom Impairment domain were too difficult to measure. Response ranges in the other two domains demonstrated acceptable difficulty. These results from the study indicate that this new patient-reported outcome instrument can be used with patients treated with brachytherapy for uveal melanoma. Providers could use this instrument to help inform post-treatment management.

Psychometric properties of the Coronavirus Anxiety Scale based on Classical Test Theory (CTT) and Item Response Theory (IRT) models among Chinese front-line healthcare workers

BackgroundSince March 2022, the COVID-19 epidemic has rebounded widely and frequently in China. Healthcare workers have faced grand challenges such as soaring COVID-19 patients, being busy with the nucleic acid screening of all the populations in the epidemic areas every day, and testing positive for COVID-19, all of which contributed to anxiety easily according to the Conservation of Resources theory. However, anxiety among healthcare workers is not only associated with personal health but also adversely affects the quality of health services. Therefore, it is crucial to search for suitable tools to monitor the anxiety related to COVID-19 among healthcare workers. The current study aimed to test the Coronavirus Anxiety Scale (CAS) in Chinese healthcare workers.MethodsThe current study employed a cross-sectional design. The CAS was translated into Chinese. Then, according to Classical Test Theory (CTT) and Item Response Theory (IRT) models, the psychometric properties of the Chinese version were measured among 811 healthcare workers.ResultsThe split‐half reliability was 0.855. The Cronbach’s α coefficient was 0.895. The retest coefficient was 0.901 with 10 days as the retest interval. The content validity index was 0.920. In exploratory factor analysis, one common factor was extracted and explained 72.559% of the total variance. All item load values on the common factor ranged from 0.790 to 0.885, and the communality of each item ranged from 0.625 to 0.784. With confirmatory factor analysis, the single factor model showed an excellent goodness-of-fit, chi-square/degree of freedom (χ2/df) = 3.339, goodness of fit index (GFI) = 0.992, adjusted goodness of fit index (AGFI) = 0.975, root-mean-square error of approximation (RMSEA) = 0.054, root mean square residual (RMR) = 0.005, incremental fit index (IFI) = 0.967, Tucker-Lewis index (TLI) = 0.932, and comparative fit index (CFI) = 0.966. The multiple-group confirmatory factor analysis revealed the invariance measuring anxiety of COVID-19 was in similar ways across ages, hospital degrees, and professional titles. With convergent validity, the CAS was positively correlated with post-traumatic stress disorder (r = 0.619, P < 0.001), fear of COVID (r = 0.550, P < 0.001), and depression (r = 0.367, P < 0.001). According to IRT models, the results showed that all item discrimination parameters were higher than 1.70 and difficulty parameters ranged from 1.13 to 2.83.ConclusionThe Chinese version of CAS has good psychometric properties in healthcare workers after China adjusted the COVID-19 management measures during the COVID-19 Omicron epidemic, and can be used for assessing the anxiety associated with COVID-19 in Chinese healthcare workers.

ITEM RESPONSE THEORY VALIDATION OF THE FORGOTTEN JOINT SCORE FOR PEOPLE UNDERGOING TOTAL KNEE ARTHROPLASTY

AbstractBackgroundThe Forgotten Joint Score (FJS) is a 12-item patient reported outcome measurement instrument. It was developed with classical test theory, without testing assumptions such as unidimensionality (all items reflect one underlying factor), appropriate weighting of each item, no differential item function (DIF, different groups answer the same way), and monotonicity (people with higher function have higher score). We applied item response theory (IRT) to improve the validity of FJS to contemporary standards to optimise it for ongoing use.Research QuestionsDoes the FJS reflect one latent trait? Can an IRT model be fitted to the FJS to provide interval-scaled measurement?MethodologyParticipants undergoing primary total knee replacement provided pre-operative and post-operative (6-months) responses for FJS. An exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and Mokken analysis were conducted. The data were fitted to a graded response model (GRM).Results1288 response patterns were analysed. EFA showed a one factor model (all 12 items load to one underlying trait). CFA demonstrated excellent model fit (X2 &lt;0.001, Tucker Lewis Index=0.96, Comparative Fit Index=0.96). Items did not have equal weighting. The FJS demonstrated good monotonicity with no differential item functioning by sex, age, or body mass index.ConclusionsThe FJS meets key validity assumptions supporting its use in clinical practice and research. The IRT-adapted FJS provides continuous measurements with greater granularity including individual measurement error. This adapted score has advantages over traditional FJS scoring, being interval scaled (using GRM) and can be retrospectively applied to existing response sets.

3-D-Printed Models for Temporal Bone Training: A Validity Study

Objective3-D printing offers convenient and low-cost mastoidectomy training; nonetheless, training benefits using 3-D-printed temporal bones remain largely unexplored. In this study, we have collected validity evidence for a low-cost, 3-D-printed temporal bone for mastoidectomy training and established a credible pass/fail score for performance on the model.Study designA prospective educational study gathering validity evidence using Messick's validity framework.SettingSeven Danish otorhinolaryngology training institutions.ParticipantsEighteen otorhinolaryngology residents (novices) and 11 experienced otosurgeons (experts).InterventionResidents and experienced otosurgeons each performed two to three anatomical mastoidectomies on a low-cost, 3-D-printed temporal bone model produced in-house. After drilling, mastoidectomy performances were rated by three blinded experts using a 25-item modified Welling scale (WS).Main outcome measureValidity evidence using Messick's framework including reliability assessment applying both classical test theory and Generalizability theory.ResultsNovices achieved a mean score of 13.9 points; experienced otosurgeons achieved 23.2 points. Using the contrasting groups method, we established a 21/25-point pass/fail level. The Generalizability coefficient was 0.91, and 75% of the score variance was attributable to participant performance, indicating a high level of assessment reliability. Subsequent D studies revealed that two raters rating one performance or one rater rating two performances were sufficiently reliable for high-stakes assessment.ConclusionValidity evidence supports using a low-cost, 3-D-printed model for mastoidectomy training. The model can be printed in-house using consumer-grade 3-D printers and serves as an additional training tool in the temporal bone curriculum. For competency-based training, we established a cut-off score of 21 of 25 WS points using the contrasting groups method.

Item response theory approach to ethnocentrism

IntroductionAlthough ethnocentrism is one of the fundamental concepts in the social sciences, its study has been impeded by a diversity of conceptualizations and measures. In recent years, a growing number of political scientists and psychologists have undertaken in-depth research into ethnocentrism. In addition, researchers have recently proposed a comprehensive reconceptualization of ethnocentrism and developed a new Ethnocentrism scale. There is strong evidence for this scale's reliability and validity in indexing ethnocentrism, but like most measures in psychology and political science, this scale is based on classical test theory. Item response theory (IRT) is a powerful psychometric technique that can provide a much more sophisticated test of test performance and is currently under-utilized in research.MethodsWe performed IRT to assess the psychometric properties of the Ethnocentrism scale on a sample of 4,187 participants.ResultsThe scale's items had strong psychometric properties to capture the ethnocentrism latent construct, particularly in the below average to above average range. Men required marginally lower levels of ethnocentrism to endorse less socially acceptable items than women (items relating to superiority, purity, or exploitativeness). When compared to liberals, conservatives responded more readily to nearly all ethnocentrism items. Given this variation, the IRT approach highlighted that future measurements must adjust for differential item functioning, albeit more for political orientation than gender identity.DiscussionThe findings detail how IRT can enhance measurement in political science and demonstrate the implications for how gender and political ideology may affect the differential performance of items.

Book Review of Rasch Models for Solving Measurement Problems: Invariant Measurement in the Social Sciences by Engelhard Jr. and Wang

As a paradigm shift from classical test theory, Rasch measurement theory introduces a framework of scales that is capable of producing invariant measurement, which plays an increasingly important role in solving practical measurement problems in the social sciences, psychometrics, and health sciences. Researchers have increasingly adopted Rasch measurement to develop and validate scales in a variety of educational and psychological contexts (e.g. Mendoza Yan, 2021; Yan Pastore, 2022). Rasch measurement is often used in the validation of scales in conjunction with structural equation models (SEM), which provide meaningful answers to a variety of measurement questions. However, it remains unfamiliar to many researchers, practitioners, and educators who have embraced classical test theory.

Validation of The Purpose in Life Scale-Short Form in an Ecuadorian Sample: factor analysis, reliability and graded response model

Introduction: The purpose in life is analyzed within psychological well-being, it deals with the meaning of life that people have, which has implications in areas such as mental health. Currently, precise instrumentation is required for its assessment of the Ecuadorian population, which at the moment is limited. Objective: To corroborate the unidimensional structure of the Purpose in Life Scale-Short version (PIL-SF), the equivalence of measurement according to gender, the reliability and the parameters of discrimination and difficulty in a sample of Ecuadorian adults. Methods: Instrumental study of the PIL-SF under the precepts of Classical Test Theory and Item Response Theory. Participants: 743 Ecuadorian adults (64.2% women and 45.8% men) aged 18 to 73 years (M = 24.7, SD = 7.9). Results: The unifactorial structure of the PIL-SF with adequate adjustment was confirmed. In addition, the PIL-SF is invariant at the strong level based on gender and no differences are presented at the level of latent means. The internal consistency reliability is acceptable per group and the discrimination and item difficulty parameters are adequate. Conclusion: The PIL-SF is a valid, reliable, and accurate tool to measure the Purpose in Life construct in Ecuadorian adults.