Principal Component Analysis Of Residuals Research Articles

A Rasch analysis of nurses’ ethical sensitivity to the norms of the code of conduct

To develop an instrument to measure nurses' ethical sensitivity and, secondarily, to use this instrument to compare nurses' ethical sensitivity between groups. Professional codes of conduct are widely accepted guidelines. However, their efficacy in daily nursing practice and influence on ethical sensitivity is controversial. A descriptive cross-sectional study was conducted. One hundred and forty-three registered nurses from Barcelona (Spain) participated in the study, of whom 45.83% were working in primary health care and 53.84% in hospital wards. A specifically designed confidential, self-administered questionnaire assessing ethical sensitivity was developed. Knowledge of the nursing code and data on ethical sensitivity were summarised, with the quality of the questionnaire assessed using Rasch analysis. Item on knowledge of the code showed that one-third of nurses knew the contents of the code and two-thirds had limited knowledge. To fit the Rasch model, it was necessary to rescore the rating scale from five to three categories. Residual principal components analysis confirmed the unidimensionality of the scale. Three items of the questionnaire presented fit problems with the Rasch model. Although nurses generally have high ethical sensitivity to their code of conduct, differences were found according to years of professional practice, place of work and knowledge of the code (p<0.05). The questionnaire showed acceptable psychometric properties to achieve the proposed objective. Nurses' ethical sensitivity to the norms of the code was high. However, many factors might influence the degree of ethical sensitivity. Further research to measure ethical sensitivity using invariant measures such as Rasch units would be valuable. Other factors, such as assertiveness or courage, should be considered to improve ethical sensitivity to the code of conduct. Rigorous measurement studies and analysis in applied ethics are needed to assess ethical performance in practice.

Further validation of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in the UK veterinary profession: Rasch analysis

To examine the psychometric properties of the 14-item Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in the UK veterinary profession by the application of Rasch analysis, and to assess the external construct validity of the derived interval scale measurements. Data sets were derived from two independent cross-sectional surveys of the veterinary profession (n = 8,829 and n = 1,796). Rasch analysis (n = 500) included response option thresholds ordering, tests of fit, differential item functioning, targeting, response dependency, and person separation index (PSI). Unidimensionality was evaluated by principal component analysis of residuals. The findings were validated across further subsamples from both data sets. The external construct validity of the Rasch-fitting item set was evaluated by associations with other measures of psychological health or psychosocial work characteristics. Data for the original 14 items deviated significantly from Rasch model expectations (chi-square = 558.2, df = 112, P = <0.001, PSI = 0.918). A unidimensional 7-item scale (Short WEMWBS, SWEMWBS) with acceptable fit to the model (chi-square = 58.8, df = 56, P = 0.104, PSI = 0.832) was derived by sequential removal of the most misfitting items. The external construct validity of SWEMWBS was supported. SWEMWBS has robust interval-level measurement properties which support its suitability as an indicator of population mental health and well-being in this occupational group with elevated suicide risk.

Rasch analysis informed modifications to the Work Instability Scale for Rheumatoid Arthritis for use in work-related upper limb disorders

Objective The Work Instability Scale for Rheumatoid Arthritis (RA-WIS) is a promising prognostic tool for future work disability outcomes. Rasch analysis was conducted to examine the psychometric performance of the RA-WIS in work-related upper limb disorders. Study Design and Setting Eligible injured workers ( n = 396) attending a Shoulder and Elbow Specialty clinic participated in a 1-year study with surveys fielded at four time points. Fit of RA-WIS data (range, 0–23 with 23 = highest work instability) to the Guttman structure was evaluated by item-fit, person-fit, item-trait interaction statistics, and the person separation index (PSI). Differential item functioning (DIF) was evaluated by two-way analyses of variance of the residuals across age, sex, location of injury, perceived exertion at work, and repeated testing over time. Unidimensionality was evaluated by principal component analysis of residuals and tests of local independence. Results RA-WIS data showed significant deviations from the Guttman structure (item-trait interaction χ 2 = 181.6, P < 0.0001, PSI = 0.86). A sequential removal of the six most misfitting items was performed, resulting in a 17-item scale that met all Rasch model expectations ( χ 2 = 57.5, P = 0.007, PSI = 0.83), including unidimensionality, local independence of items, and the absence of DIF across all tested factors. Conclusion A new 17-item Upper Limb Work Instability Scale that satisfied assumptions for interval-level scaling was derived.

Rasch analysis of the Psychiatric Out-Patient Experiences Questionnaire (POPEQ).

BackgroundThe Psychiatric Out-Patient Experiences Questionnaire (POPEQ) is an 11-item core measure of psychiatric out-patients experiences of the perceived outcome of the treatment, the quality of interaction with the clinician, and the quality of information provision. The POPEQ was found to have evidence for reliability and validity following the application of classical test theory but has not previously been assessed by Rasch analysis.MethodsTwo national postal surveys of psychiatric outpatients took place in Norway in 2004 and 2007. The performance of the POPEQ, including item functioning and differential item functioning, was assessed by Rasch analysis. Principal component analysis of item residuals was used to assess the presence of subdimensions.Results6,677 (43.3%) and 11,085 (35.2%) psychiatric out patients responded to the questionnaire in 2004 and 2007, respectively. All items in the scale were retained after the Rasch analysis. The resulting scale had reasonably good fit to the Rasch model. The items performed the same for the two survey years and there was no differential item functioning relating to patient characteristics. Principal component analysis of the residuals confirmed that the measure to a high degree is unidimensional. However, the data also reflects three potential subscales, each relating to one of the three included aspects of health care.ConclusionsThe POPEQ had excellent psychometric properties and Rasch analysis further supported the construct validity of the scale by also identifying the three subdimensions originally included as components in the instrument development. The 11-item instrument is recommended in future research on psychiatric out-patient experiences. Future development may lead to the construction of more precise measures of the three subdomains that the POPEQ is based on.

The Determinants of Credit Default Swap Premia

AbstractVariables that in theory determine credit spreads have limited explanatory power in existing empirical work on corporate bond data. We investigate the linear relationship between theoretical determinants of default risk and default swap spreads. We find that estimated coefficients for a minimal set of theoretical determinants of default risk are consistent with theory and are significant statistically and economically. Volatility and leverage have substantial explanatory power in univariate and multivariate regressions. A principal component analysis of residuals and spreads indicates limited evidence for a residual common factor, confirming that the theoretical variables explain a significant amount of the variation in the data.

Validating the Falls Behavioural (FaB) scale for older people: A Rasch analysis

Purpose. Rasch modelling was used to establish the validity and robustness of the Falls Behavioural (FaB) Scale for Older people.Methods. The sample comprised 678 community-residing elderly people aged 65 – 98 years. Data were analysed by calculating goodness of fit statistics, principal components analysis of residuals and by exploring the effectiveness of the category rating response-scale.Results. A partial-credit rating scale was the best fitting solution and the major change to the original version of the FaB. Analysis supported a 29-item intervention version and a briefer 24-item outcome evaluation (research) version. The latter produced item mean infit statistics of 1.00 (Z = 0.0, SD = 0.33) and mean outfit statistics of 1.03 (Z = 0.0, SD = 0.53), a person separation of 2.36 and internal reliability of 0.85.Conclusion. The 29 item partial rating scale is valid, reliable and would be useful in clinical situations when used as a prompt for discussion and in raising clients' awareness of potential hazards; it also can be used as an outcome measure. The short form is a useful alternate for evaluating the effectiveness of fall reduction interventions that aim to encourage protective strategies when negotiating the environment, mobilizing and doing activities of daily living. Both scales would be improved by adding very difficult and very easy items to increase the range of ability levels of the people to whom it can be applied with precision.

Unidimensionality in the Rasch model: how to detect and interpret

Unidimensionality, that is the items in a questionnaire measure only a single construct, is a fundamental requirement for the Rasch model. The paper deals with the detection of unidimensionality making use of principal components analysis of residuals and item fit statistics. Simulated bi-dimensional data sets are analized in order to find regolarities in the behavoiur of these statistical tools. The results are applied to a real database coming from the satisfaction section of the first national survey concerning the social services sector carried out in Italy

A combined-method psychometric analysis recommended modification of the multidimensional health locus of control scales

Objective The Multidimensional Health Locus of Control (MHLC) scales are widely used to measure beliefs about determinants of persons' health. We evaluated the scales over the largest-ever disease-specific sample of subjects using a combined-method psychometric approach. Study Design and Setting We performed a secondary analysis of data from 1,206 subjects from three osteoarthritis studies, using Rasch analysis and confirmatory factor analysis simultaneously. Differential item functioning (DIF) by gender and data source, scale dimensionality, and item fit were examined. The Rasch model fit the data if Rasch residual principal components analysis (PCA) corroborated three distinct dimensions and item fit statistics fell between 0.80 and 1.20. The confirmatory factor (CFA) model fit the data if factor loadings exceeded 0.50 for all items. Results DIF by gender or data source was not materially evident for any items. PCA supported existence of three dimensions in the data. Both Rasch and CFA models fit the data for 16 items; two items were detected as misperforming. When these items were removed, fit of both models improved. Conclusion Results of this large-sample evaluation of the MHLC scales corroborated earlier findings that removal of certain items improves the scales. The combined Rasch–CFA approach provided better insight to scale performance problems than either method alone provided.

Estudo sobre a unidimensionalidade do teste Matrizes Progressivas Coloridas de Raven

This study assessed the adjustment of the Rasch model concerning unidimensionality of Raven's Colored Standard Progressive Matrices. Four hundred and forty-one (441) elementary school children, of both genders, attending first to fourth grade were investigated. Considering that residuals may be enough to violate the intrinsic unidimensionality of the items, residual principal component analysis was used to assess the possibility of this violation. Items with higher factorial loading relating to the positive and negative dimensions on the first factor were selected, in respect to the test as a whole and to each subset in particular. These items were re-analyzed with the Rasch model within each data group. Then the positive and negative factor measures were correlated. Results suggested the possibility of other dimensions besides those extracted by Rasch model based on the test and subset B, though the correlation coefficients of the other subsets were close to rejection.

Neural network pruning applied to real exchange rate analysis

AbstractNeural networks are fitted to real exchange rates of several industrialized countries. The size and topology of the networks is found through the use of multiple correlation coefficients, principal component analysis of residuals and graphical analysis of network output per hidden layer cell and input layer cell. These pruned neural networks are good approximations to varying non‐linear trends in real exchange rates. Non‐linear dynamic analysis shows that the long‐term equilibrium values of several European currencies correspond to the actual values within the European Monetary System. Based on its long‐term equilibrium value, the Euro appears to be undervalued vis‐à‐vis the US dollar at the introduction of the Euro on 1 January 1999. Copyright © 2002 John Wiley &amp; Sons, Ltd.

The evolution of demographic tactics in lizards: a test of some hypotheses concerning life history evolution

AbstractWe analyze, with an augmented data base, patterns of covariation of the three primary demographic parameters (age at maturity, fecundity, adult survival, all measured in the same unit of time) in lizards. This also constitutes a first attempt to use all three of these parameters for this group of species. We attempt to place these analyses in the framework of recent theories on life history evolution (Ferrière and Clobert, 1992; Charnov, 1993). Life history data were collected from the literature and from our original work, and a composite phylogeny was assembled, based on a variety of published sources. Using a phylogenetically based statistical method (independent contrasts), the allometric (log‐log) relationship of fecundity (and of clutch size) in relation to snout‐vent length was found to differ significantly between the two major clades of extant lizards, Iguania (43 species in our data set) and Scleroglossa (47 species). We therefore emphasize analyses done separately for the two clades. Without removing correlations with body size, the relationships between fecundity and survival, and between fecundity and age at maturity, were also found to differ between clades, which differs from Charnov's (1993) predictions. When correlations with body size were removed statistically, however, the two clades did not differ significantly in these relationships. In a principal components analysis (PCA) of the three demographic variables plus snout‐vent length, the first axis explained the majority (53–57%) of variation in both clades, while the second axis explained 27–31% of the variation and loaded mainly on fecundity. In a PCA of size‐adjusted demographic variables residuals (from log‐log regressions on snout‐vent length), the first axis explained 66–68% of the variation and was clearly interpretable as the classical “slow‐fast” continuum, which has been described in birds and mammals. The PCA of residuals did not provide clear evidence of additional significant patterns of covariation. However, the rate of evolution of mortality (size‐corrected), but not of fecundity or age at maturity, differed significantly between clades. Furthermore, fecundity and age at maturity, both corrected for variation in adult mortality (in addition to body size), were still significantly related, indicating the existence of other patterns of variation in these life history traits. In other words, the ratios between age at maturity and adult mortality, or between fecundity and adult mortality, were not found to be invariant, because the variation not accounted for by these ratios was significantly associated with variation in another variable. This result contradicts the prediction of Charnov (1993), and suggests the existence of other directions of evolution in these life history traits.