For unidimensional item response theory (UIRT) models, three linking methods, which are the separate, concurrent, and fixed parameter calibration methods, have been developed and widely used in applications such as vertical scaling, differential item functioning, computerized adaptive testing (CAT), and equating. By contrast, even though a few studies have compared the separate and concurrent calibration methods for full multidimensional IRT (MIRT) models or applied the concurrent calibration method to vertical scaling using the bifactor model, no study has yet provided technical descriptions of the concurrent and fixed parameter calibration methods for any MIRT models. Thus, the purpose of this dissertation was to extend the concurrent and fixed parameter calibration methods for UIRT models to the two-tier item factor analysis model. In addition, the relative performance of the separate, concurrent, and fixed parameter calibration methods was compared in terms of the recovery of item parameters and accuracy of IRT observed score equating using both real and simulated datasets. The separate, concurrent, and fixed parameter calibration methods well recovered the item parameters, with the concurrent calibration method performing slightly better than the other two linking methods. Despite the comparable performance of the three linking methods in terms of the recovery of item parameters, however, some discrepancy was observed between the IRT observed score equating results obtained with the three linking methods. In general, the concurrent calibration method provided equating results with the smallest equating error, whereas the separate calibration method provided equating results with the largest equating error due to the largest standard error of equating. The performance of the fixed parameter calibration method depended on the proportion of common items. When the proportion was , the fixed parameter calibration method provided more biased equating results than the concurrent calibration method because of the underestimated specific slope parameters. However, when the proportion of common items was 40%, the fixed parameter calibration method worked as well as the concurrent calibration method.

Apathy, defined as a decrease in purposeful or goal-directed behavior, is common in many neurological disorders. The assessment of apathy in these disorders is important as apathy is associated with differential engagement and response to treatment and future cognitive and functional decline. Although apathy is often described as including three separate symptom dimensions, reflecting diminished interest, action, and emotional expression, investigations of the factor structure of apathy symptoms have been limited by the use of scales which do not comprehensively assess all of three of the proposed dimensions. The current study aimed to develop a novel informant report measure of apathy symptoms, investigate the factor structure of apathy symptoms, and examine the relationship of different types of apathy symptoms to several clinically relevant variables. Participants included 249 informants who reported on an individual with (n=210) or without (n=39) a neurological or psychiatric condition. Results showed the best fitting model of apathy symptoms was a bifactor model in which apathy could be represented as a global dimension with three separate, specific symptom factors reflecting diminished interest and initiative, asociality, and diminished emotional and verbal expression. In general, apathy was associated with poorer cognitive functioning, greater functional impairment, and higher caregiver distress. The specific symptom factors differed somewhat in their association with those same variables, highlighting the utility of measuring different types of symptoms in addition to overall apathy. Future work will refine the apathy measure developed in this study and test the obtained bifactor symptom model in an independent sample.

Given increased evidence related to the importance of fostering life satisfaction in the overall population (Diener & Diener, 1996), as well as recent suggestions regarding the importance of increasing positive academic and social outcomes for children with ADHD (DuPaul, 2007), it is important to gain a clearer understanding of how life satisfaction may be related to symptoms of inattention and hyperactivity/impulsivity. Research on the relationship between life satisfaction and symptoms of inattention, hyperactivity, and impulsivity is currently limited to two studies (Gudjonsson et al., 2009; Ogg et al., 2014). The current study investigated the relationship between symptoms of inattention and hyperactivity/impulsivity and reports of global life satisfaction in 399 high school students. This study used the bifactor model to conceptualize ADHD given that this model provided the best fit when compared to other models of ADHD in the current study and given that there is substantial evidence in the current literature to support the use of this model (Martel, von Eye, & Nigg, 2010). Structural equation modeling results demonstrated that the general factor of ADHD was a significant predictor of life satisfaction when students rated ADHD symptoms, and the inattention factor of ADHD was a significant predictor of life satisfaction when teachers rated ADHD symptoms. In addition, because depressive symptoms have been associated with life satisfaction and inattention, hyperactivity, and impulsivity, the current study examined if life satisfaction moderated or mediated the relationship between inattention, hyperactivity, and impulsivity and depressive symptoms. Results of the present study suggested that life satisfaction serves as a potential but weak moderator in the relationship between general ADHD and depression when symptoms of ADHD were rated by teachers. Results also demonstrated that life satisfaction mediated the relationship between general ADHD symptoms and depressive symptoms when ADHD symptoms were rated by students, and life satisfaction mediated the relationship between inattentive symptoms and depressive symptoms when ADHD symptoms were rated by teachers. The current study contributes to existing literature on life satisfaction given that there are currently only two studies, one which was conducted with an adult population and one of which was conducted with a middle school population, specifically examining levels of life satisfaction in individuals with symptoms of ADHD. The results of this study provide additional confirmation of the negative relationship between ADHD symptoms and life satisfaction. Moreover, this study was the first to examine how life satisfaction may play a role in the relationship between symptoms of ADHD and depressive symptoms. This study supports that life satisfaction primarily plays a mediating role in the relationship between ADHD symptoms and depressive symptoms and provides support for further examination of this role in future studies.

There is no information in Peru on the prevalence of mental health problems associated with COVID-19 in older adults. In this sense, the aim of the study was to gather evidence on the factor structure, criterion-related validity, and reliability of the Spanish version of the Fear of COVID-19 Scale (FCV-19S) in this population. The participants were 400 older adults (mean age = 68.04, SD = 6.41), who were administered the Fear of COVID-19 Scale, Revised Mental Health Inventory-5, Patient Health Questionnaire-2 items, and Generalized Anxiety Disorder Scale 2 items. Structural equation models were estimated, specifically confirmatory factor analysis (CFA), bifactor CFA, and structural models with latent variables (SEM). Internal consistency was estimated with composite reliability indexes (CRI) and omega coefficients. A bifactor model with both a general factor underlying all items plus a specific factor underlying items 1, 2, 4, and 5 representing the emotional response to COVID better represents the factor structure of the scale. This structure had adequate fit and good reliability, and additionally fear of COVID had a large effect on mental health. In general, women had more fear than men, having more information on COVID was associated to more fear, while having family or friends affected by COVID did not related to fear of the virus. The Spanish version of the Fear of COVID-19 Scale presents evidence of validity and reliability to assess fear of COVID-19 in the Peruvian older adult population.

The primary goal of this study was to develop a new procedure for estimating decision consistency and accuracy indices using the bifactor and testlet response theory (TRT) models. This study is the first to investigate decision consistency and accuracy from a multidimensional perspective, and the results have shown that the bifactor model at least behaved in way that met the author's expectations and represents a potential useful procedure. The TRT model, on the other hand, did not meet the author's expectations and generally showed poor model performance. The multidimensional decision consistency and accuracy indices proposed in this study appear to provide good performance, at least for the bifactor model, in the case of a substantial testlet effect. For practitioners examining a test containing testlets for decision consistency and accuracy, a recommended first step is to check for dimensionality. If the testlets show a significant degree of multidimensionality, then the usage of the multidimensional indices proposed can be recommended as the simulation study showed an improved level of performance over unidimensional IRT models. However, if there is a not a significant degree of multidimensionality then the unidimensional IRT models and indices would perform as well, or even better, than the multidimensional models. Another goal of this study was to compare methods for numerical integration used in the calculation of decision consistency and accuracy indices. This study investigated a new method (M method) that sampled ability estimates through a Monte-Carlo approach. In summary, the M method seems to be just as accurate as the other commonly used methods for numerical integration. However, it has some practical advantages over the D and P methods. As previously mentioned, it is not as nearly as computationally intensive as the D method. Also, the P method requires large sample sizes. In addition, the P method has conceptual disadvantage in that the conditioning variable, in theory, should be the true theta, not an estimated theta. The M method avoids both of these issues and seems to provide equally accurate estimates of decision consistency and accuracy indices, which makes it a strong option particularly in multidimensional cases.

Bifactor Item Response Theory (IRT) models are presented as a plausible structure for psychological measures with a primary scale and two or more subscales. A bifactor graded response model, appropriate for polytomous categorical data, was fit to two university counseling center datasets (N=4,679 and N=4,500) of Outcome-Questionnaire-45.2 (OQ) psychotherapy intake data. The bifactor model showed superior fit compared to a unidimensional IRT model. IRT item parameters derived from the bifactor model show that items discriminate well on the primary scale. Items on the OQ's subscales maintain some discrimination ability over and above the primary scale. However, reliability estimates for the subscales, controlling for the primary scale, suggest that clinical use should likely proceed with caution. Item difficulty or severity parameters reflected item content well, in that increased probability of endorsement was found at high levels of distress for items tapping severe symptomatology. Increased probability of endorsement was found at lower levels of distress for items tapping milder symptomatology. Analysis of measurement invariance showed that item parameters hold equally across gender for most OQ items. A subset of items was found to have item parameters non-invariant across gender. Implications for research and practice are discussed, and directions for future work given.

Enjeu important pour le marketing des seniors, le concept de bien vieillir demeure peu investigué par la recherche en marketing. Nous introduisons un nouveau concept, le Bien Vieillir Désiré (BVD), qui fait référence aux objectifs psychologiques, physiques, sociaux et financiers, poursuivis dans la quête du bien vieillir. Nous en proposons un modèle de mesure bifactoriel, fiable et valide, en quatre dimensions : le BVD général, le BVD physique, le BVD social et le BVD financier. Son influence est testée sur huit comportements de consommation relatifs aux secteurs suivants : alimentation, e-santé, chirurgie esthétique, loisirs, placements financiers, réseaux sociaux et sites de rencontres. L’échelle de mesure et un modèle global antécédents-manifestations-effets sont validés à partir d’un échantillon de 900 seniors âgés de 50 à 80 ans. Les résultats suggèrent le développement d’une nouvelle approche marketing des seniors : le marketing du bien vieillir. Son investigation et sa mise en œuvre sont ancrées dans quatre concepts clés : le BVD, le vieillissement perçu, les attentes d’ajustement au vieillissement et la consommation du bien vieillir. / Aging well is now a key stake for senior marketing, yet this concept remains little investigated by consumer research. A new concept is introduced in marketing research: Desired Aging Well (DAW), which refers to the psychological, physical, social and financial objectives, pursued in the quest for aging well. This research provides a reliable and valid bifactor measurement model for Desired Aging Well, in four dimensions: general DAW, physical DAW, social DAW and financial DAW. Its influence is tested on eight consumer behaviors related to the following sectors: food, e-health, plastic surgery, leisure, financial investments, social networks and dating sites. The Desired Aging Well scale and the overall antecedents-manifestations-effects model are validated on a sample of 900 French senior people aged from 50 to 80. The results suggest the development of a new marketing approach for seniors: aging well marketing. Its investigation and implementation are rooted in four key concepts: Desired Aging Well, perceived aging, adjustment to aging expectations and aging well consumption.