33 resultados para reliability and validity

em Aston University Research Archive


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PURPOSE: To investigate the MacDQoL test-retest reliability and sensitivity to change in vision over a period of one year in a sample of patients with age-related macular degeneration (AMD). DESIGN: A prospective, observational study. METHOD: Patients with AMD from an ophthalmologist's list (n = 135) completed the MacDQoL questionnaire by telephone interview and underwent a vision assessment on two occasions, one year apart. RESULTS: Among participants whose vision was stable over one year (n = 87), MacDQoL scores at baseline and follow-up were highly correlated (r = 0.95; P < .0001). Twelve of the 22 scale items had intraclass correlations of >.80; only two were correlated <.7. There was no difference between baseline and follow-up scores (P = .85), indicating excellent test-retest reliability. Poorer quality of life (QoL) at follow-up, measured by the MacDQoL present QoL overview item, was associated with deterioration in both the better eye and binocular distance visual acuity [VA] (r = 0.29; P = .001, r = 0.21; P = .016, respectively; n = 135). There was a positive correlation between deterioration in the Mac. DQoL average weighted impact score and deterioration in both binocular near VA and reading speed (r = 0.20; P = .019, r = 0.18; P = .041, respectively; n = 135). CONCLUSION: The MacDQoL has excellent test-retest reliability. Its sensitivity to change in vision status was demonstrated in correlational analyses. The measure indicates that the negative impact of AMD on QoL increases with increasing severity of visual impairment.

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PURPOSE: To validate a new miniaturised, open-field wavefront device which has been developed with the capacity to be attached to an ophthalmic surgical microscope or slit-lamp. SETTING: Solihull Hospital and Aston University, Birmingham, UK DESIGN: Comparative non-interventional study. METHODS: The dynamic range of the Aston Aberrometer was assessed using a calibrated model eye. The validity of the Aston Aberrometer was compared to a conventional desk mounted Shack-Hartmann aberrometer (Topcon KR1W) by measuring the refractive error and higher order aberrations of 75 dilated eyes with both instruments in random order. The Aston Aberrometer measurements were repeated five times to assess intra-session repeatability. Data was converted to vector form for analysis. RESULTS: The Aston Aberrometer had a large dynamic range of at least +21.0 D to -25.0 D. It gave similar measurements to a conventional aberrometer for mean spherical equivalent (mean difference ± 95% confidence interval: 0.02 ± 0.49D; correlation: r=0.995, p<0.001), astigmatic components (J0: 0.02 ± 0.15D; r=0.977, p<0.001; J45: 0.03 ± 0.28; r=0.666, p<0.001) and higher order aberrations RMS (0.02 ± 0.20D; r=0.620, p<0.001). Intraclass correlation coefficient assessments of intra-sessional repeatability for the Aston Aberrometer were excellent (spherical equivalent =1.000, p<0.001; astigmatic components J0 =0.998, p<0.001, J45=0.980, p<0.01; higher order aberrations RMS =0.961, p<0.001). CONCLUSIONS: The Aston Aberrometer gives valid and repeatable measures of refractive error and higher order aberrations over a large range. As it is able to measure continuously, it can provide direct feedback to surgeons during intraocular lens implantations and corneal surgery as to the optical status of the visual system.

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BACKGROUND: Gilles de la Tourette syndrome (GTS) is a chronic childhood-onset neuropsychiatric disorder with a significant impact on patients' health-related quality of life (HR-QOL). Cavanna et al. (Neurology 2008; 71: 1410-1416) developed and validated the first disease-specific HR-QOL assessment tool for adults with GTS (Gilles de la Tourette Syndrome-Quality of Life Scale, GTS-QOL). This paper presents the translation, adaptation and validation of the GTS-QOL for young Italian patients with GTS. METHODS: A three-stage process involving 75 patients with GTS recruited through three Departments of Child and Adolescent Neuropsychiatry in Italy led to the development of a 27-item instrument (Gilles de la Tourette Syndrome-Quality of Life Scale in children and adolescents, C&A-GTS-QOL) for the assessment of HR-QOL through a clinician-rated interview for 6-12 year-olds and a self-report questionnaire for 13-18 year-olds. RESULTS: The C&A-GTS-QOL demonstrated satisfactory scaling assumptions and acceptability. Internal consistency reliability was high (Cronbach's alpha > 0.7) and validity was supported by interscale correlations (range 0.4-0.7), principal-component factor analysis and correlations with other rating scales and clinical variables. CONCLUSIONS: The present version of the C&A-GTS-QOL is the first disease-specific HR-QOL tool for Italian young patients with GTS, satisfying criteria for acceptability, reliability and validity. © 2013 - IOS Press and the authors. All rights reserved.

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Over the past forty years the corporate identity literature has developed to a point of maturity where it currently contains many definitions and models of the corporate identity construct at the organisational level. The literature has evolved by developing models of corporate identity or in considering corporate identity in relation to new and developing themes, e.g. corporate social responsibility. It has evolved into a multidisciplinary domain recently incorporating constructs from other literature to further its development. However, the literature has a number of limitations. It remains that an overarching and universally accepted definition of corporate identity is elusive, potentially leaving the construct with a lack of clear definition. Only a few corporate identity definitions and models, at the corporate level, have been empirically tested. The corporate identity construct is overwhelmingly defined and theoretically constructed at the corporate level, leaving the literature without a detailed understanding of its influence at an individual stakeholder level. Front-line service employees (FLEs), form a component in a number of corporate identity models developed at the organisational level. FLEs deliver the services of an organisation to its customers, as well as represent the organisation by communicating and transporting its core defining characteristics to customers through continual customer contact and interaction. This person-to-person contact between an FLE and the customer is termed a service encounter, where service encounters influence a customer’s perception of both the service delivered and the associated level of service quality. Therefore this study for the first time defines, theoretically models and empirically tests corporate identity at the individual FLE level, termed FLE corporate identity. The study uses the services marketing literature to characterise an FLE’s operating environment, arriving at five potential dimensions to the FLE corporate identity construct. These are scrutinised against existing corporate identity definitions and models to arrive at a definition for the construct. In reviewing the corporate identity, services marketing, branding and organisational psychology literature, a theoretical model is developed for FLE corporate identity, which is empirically and quantitatively tested, with FLEs in seven stores of a major national retailer. Following rigorous construct reliability and validity testing, the 601 usable responses are used to estimate a confirmatory factor analysis and structural equation model for the study. The results for the individual hypotheses and the structural model are very encouraging, as they fit the data well and support a definition of FLE corporate identity. This study makes contributions to the branding, services marketing and organisational psychology literature, but its principal contribution is to extend the corporate identity literature into a new area of discourse and research, that of FLE corporate identity

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Because memories are not always accurate, people rely on a variety of strategies to verify whether the events that they remember really did occur. Several studies have examined which strategies people tend to use, but none to date has asked why people opt for certain strategies over others. Here we examined the extent to which people's beliefs about the reliability and the cost of different strategies would determine their strategy selection. Subjects described a childhood memory and then suggested strategies they might use to verify the accuracy of that memory. Next, they rated the reliability and cost of each strategy, and the likelihood that they might use it. Reliability and cost each predicted strategy selection, but a combination of the two ratings provided even greater predictive value. Cost was significantly more influential than reliability, which suggests that a tendency to seek and to value "cheap" information more than reliable information could underlie many real-world memory errors. © 2013 Elsevier B.V.

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In response to Chaski’s article (published in this volume) an examination is made of the methodological understanding necessary to identify dependable markers for forensic (and general) authorship attribution work. This examination concentrates on three methodological areas of concern which researchers intending to identify markers of authorship must address. These areas are sampling linguistic data, establishing the reliability of authorship markers and establishing the validity of authorship markers. It is suggested that the complexity of sampling problems in linguistic data is often underestimated and that theoretical issues in this area are both difficult and unresolved. It is further argued that the concepts of reliability and validity must be well understood and accounted for in any attempts to identify authorship markers and that largely this is not done. Finally, Principal Component Analysis is identified as an alternative approach which avoids some of the methodological problems inherent in identifying reliable, valid markers of authorship.

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The convergence on the Big Five in personality theory has produced a demand for efficient yet psychometrically sound measures. Therefore, five single-item measures, using bipolar response scales, were constructed to measure the Big Five and evaluated in terms of their convergent and off-diagonal divergent properties, their pattern of criterion correlations and their reliability when compared with four longer Big Five measures. In a combined sample (N?=?791) the Single-Item Measures of Personality (SIMP) demonstrated a mean convergence of r?=?0.61 with the longer scales. The SIMP also demonstrated acceptable reliability, self–other accuracy, and divergent correlations, and a closely similar pattern of criterion correlations when compared with the longer scales. It is concluded that the SIMP offer a reasonable alternative to longer scales, balancing the demands of brevity versus reliability and validity.

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Relationships with supervisors are a major source of negative emotions at work, but little is known about why this is so. The aim of the research was to use attachment theory (Bowlby, 1969, 1973; 1980) as a framework for investigating the nature and causes of employee negative emotional experiences, in the context of their supervisory relationships. The research was conducted in three stages. In Stage 1 two studies were conducted to develop a measure of employee perceptions of supervisor caregiving (SCS). Results indicated that the 20-item scale had good reliability and validity. Stage 2 required participants (N=183) to complete a questionnaire that was designed to examine the roles of supervisor caregiving and working models (specific and global) in determining cognitive and emotional responses to hypothetical supervisor behaviours. The results provided partial support for an Independent Effects Model. Supervisor caregiving predicted specific anxiety and avoidance. In tum, both dimensions of attachment predicted negative emotions, but this relationship was mediated by event interpretation only in the case of avoidance. Global models made a smaller but significant contribution to negative emotions overall. There was no support for an interaction effect between specific and global models in determining event interpretation. In stage 3 a sub-sample of questionnaire respondents (N=24) were interviewed about 'real-life' caregiving and negative emotional experiences in their supervisory relationships. Secure individuals experienced supervisors as consistently warm, available, and responsive. They reported few negative events or emotions. Individuals with insecure specific working models experienced rejecting or inconsistent supervisor caregiving. They were sensitised to trust and closeness issues in their relationships, and reported negative events and emotions underpinned by these themes. Overall, results broadly supported attachment theory predictions. It is concluded that an attachment theory perspective provides new insight into the nature and causes of employee negative emotions in supervisory relationships.

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Purpose - Food allergy can have a profound effect on quality of life (QoL) of the family. The Food Allergy Quality of Life—Parental Burden Questionnaire (FAQL-PB) was developed on a US sample to assess the QoL of parents with food allergic children. The aim of this study was to examine the reliability and validity of the FAQL-PB in a UK sample and to assess the effect of asking about parental burden in the last week compared with parental burden in general, with no time limit for recall given. Methods - A total of 1,200 parents who had at least one child with food allergy were sent the FAQL-PB and the Child Health Questionnaire (CHQ-PF50); of whom only 63 % responded. Results - Factor analysis of the FAQL-PB revealed two factors: limitations on life and emotional distress. The total scale and the two sub-scales had high internal reliability (all a > 0.85). There were small to moderate but significant correlations between total FAQL-PB scores and health and parental impact measures on the CHQ-PF50 (p < 0.01). Significantly greater parental burden was reported for the no-time limited compared with the time-limited version (p < 0.01). Conclusions - The FAQL-PB is a reliable and valid measure for use in the UK. The scale could be used in clinic to assess the physical and emotional quality of life in addition to the impact on total quality of life.

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Menorrhagia, or heavy menstrual bleeding (HMB), is a common gynaecological condition. As the aim of treatment is to improve women's wellbeing and quality of life (QoL), it is necessary to have effective ways to measure this. This study investigated the reliability and validity of the menorrhagia multi-attribute scale (MMAS), a menorrhagia-specific QoL instrument. Participants (n = 431) completed the MMAS and a battery of other tests as part of the baseline assessment of the ECLIPSE (Effectiveness and Cost-effectiveness of Levonorgestrel-containing Intrauterine system in Primary care against Standard trEatment for menorrhagia) trial. Analyses of their responses suggest that the MMAS has good measurement properties and is therefore an appropriate condition-specific instrument to measure the outcome of treatment for HMB. © 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2011 RCOG.

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Despite the proliferation of e-business adoption by organisations and the world-wide growth of the e-business phenomenon, there is a paucity of empirical studies that examine the adoption of e-business in the Middle East. The aim of our study is to provide insights into the salient e-business adoption issues by focusing on Saudi Arabian businesses. We developed a conceptual model for electronic business (e-business) adoption incorporating ten factors based on the technology-organization-environment framework. Survey data from 550 businesses were used to test the model and hypotheses. We conducted confirmatory factor analysis to assess the reliability and validity of constructs. The findings of the study suggest that firm technology competence, size, top management Support, technology orientation, consumer readiness, trading partner readiness and regulatory support are important antecedents of e-business adoption and utilisation. In addition, the study finds that, competitive pressure and organisational customer and competitor orientation is not a predictor for e-business adoption and utilisation. The implications of the findings are discussed and suggestions for future inquiry are presented.

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Detection of elder abuse risk is a critical issue because a lot of cases remain hidden. Screening tools can be used to detect elder abuse. However, few tools have been developed for use with caregivers. The purpose was to develop a translation and adaptation of a Spanish version of the Caregiver Abuse Screen (CASE) and to assess its validity and reliability. The CASE was then used with 211 primary caregivers. Validity and reliability were evaluated, as well as the factorial structure of the instrument. This version showed good psychometric properties. It was found to have strong internal consistency and split-half reliability as well as allowing for a good replication of the original factorial structure. Additionally, several variables related to elder abuse were linked to the CASE such as depression, burden, frequency, and reactions to problem behaviors. The version developed showed sufficient validity and reliability and could be considered as a suitable instrument to assess risks of elder abuse in a Spanish-speaking context.

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This paper describes the development and validation of a multidimensional measure of organizational climate, the Organizational Climate Measure (OCM), based upon Quinn and Rohrbaugh's Competing Values model. A sample of 6869 employees across 55 manufacturing organizations completed the questionnaire. The 17 scales contained within the measure had acceptable levels of reliability and were factorially distinct. Concurrent validity was measured by correlating employees' ratings with managers' and interviewers' descriptions of managerial practices and organizational characteristics. Predictive validity was established using measures of productivity and innovation. The OCM also discriminated effectively between organizations, demonstrating good discriminant validity. The measure offers researchers a relatively comprehensive and flexible approach to the assessment of organizational members' experience and promises applied and theoretical benefits. Copyright © 2005 John Wiley & Sons, Ltd.

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Recent and potential changes in technology have resulted in the anticipation of increases in the frequency of job changes. This has led manpower policy makers to investigate the feasibility of incorporating the employment skills of job groups in the general prediction of future job learning and performance with a view to the establishment of "job families" within which transfer might be considered reciprocally high. A structured job analysis instrument (the Position Analysis Questionnaire) is evaluated in terms of two distinct sets of scores; job dimensions and synthetically established attribute/trait profiles. Studies demonstrate that estimates of a job's structure/dimensions and requisite human attributes can be reliably established. Three alternative techniques of statistically assembling profiles of the requisite human attributes for jobs are found to have differential levels of reliability and differential degrees of validity in their estimation of the "actual" ability requirements of jobs. The utility of these two sets of job descriptors to serve as representations of the cognitive structure similarity of job groups is investigated in a study which simulates a job transfer situation. The central role of the index of similarity used to assess the relationship between "target" and "present" job is demonstrated. The relative extents to which job structure similarity and job attribute similariity are associated with positive transfer are investigated. The studies demonstrate that the dimensions of jobs, and more fruitfully their requisite human attributes can serve as bases to predict job transfer learning and performance. The nature of the index of similarity used to optimally formulate predictions of transfer is such that networks of jobs might be establishable to which current job incumbents could be expected to transfer positively. The derivation of "job families" with anticipated reciprocal transfer consequences is considered to be less appropriate.

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Background: Qualitative research has suggested that spousal carers of someone with dementia differ in terms of whether they perceive their relationship with that person as continuous with the premorbid relationship or as radically different, and that a perception of continuity may be associated with more person-centered care and the experience of fewer of the negative emotions associated with caring. The aim of the study was to develop and evaluate a quantitative measure of the extent to which spousal carers perceive the relationship to be continuous. Methods: An initial pool of 42 questionnaire items was generated on the basis of the qualitative research about relationship continuity. These were completed by 51 spousal carers and item analysis was used to reduce the pool to 23 items. The retained items, comprising five subscales, were then administered to a second sample of 84 spousal carers, and the questionnaire's reliability, discriminative power, and validity were evaluated. Results: The questionnaire showed good reliability: Cronbach's α for the full scale was 0.947, and test-retest reliability was 0.932. Ferguson's δ was 0.987, indicating good discriminative power. Evidence of construct validity was provided by predicted patterns of subscale correlations with the Closeness and Conflict Scale and the Marwit-Meuser Caregiver Grief Inventory. Conclusion: Initial psychometric evaluation of the measure was encouraging. The measure provides a quantitative means of investigating ideas from qualitative research about the role of relationship continuity in influencing how spousal carers provide care and how they react emotionally to their caring role. © 2012 International Psychogeriatric Association.