967 resultados para Parallel factor analysis


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Background: The IPEN (International Physical Activity and Environment Network) Adult project seeks to conduct pooled analyses of associations of perceived neighborhood environment, as measured by the neighborhood Environment Walkability Scale (NEWS) and its abbreviated version (NEWS-A), with physical activity using data from 12 countries. As IPEN countries used adapted versions of the NEWS/NEWS-A, this paper aimed to develop scoring protocols that maximize cross-country comparability in responses. This information is also highly relevant to non-IPEN studies employing the NEWS/NEWS-A, which is one of the most popular measures of perceived environment globally.
Methods: The following countries participated in the IPEN Adult study: Australia, Belgium, Brazil, Colombia, Czech Republic, Denmark, Hong Kong, Mexico, New Zealand, Spain, the United Kingdom, and the United States. Participants (N = 14,305) were recruited from neighborhoods varying in walkability and socio-economic status. Countries collected data on the perceived environment using a self- or interviewer-administered version of the NEWS/NEWS-A. Confirmatory Factor Analysis (CFA) was used to derive comparable country-specific measurement models of the NEWS/NEWS-A. The level of correspondence between standard and alternative versions of the NEWS/NEWS-A factor-analyzable subscales was determined by estimating the correlations and mean standardized difference (Cohen’s d) between them using data from countries that had included items from both standard and alternative versions of the subscales.
Results: Final country-specific measurement models of the NEWS/NEWS-A provided acceptable levels of fit to the data and shared the same factorial structure with six latent factors and two single items. The correspondence between the standard and alternative versions of subscales of Land use mix – access, Infrastructure and safety for walking/cycling, and Aesthetics was high. The Brazilian version of the Traffic safety subscale was highly, while the Australian and Belgian versions were marginally, comparable to the standard version. Single-item versions of the Street connectivity subscale used in Australia and Belgium showed marginally acceptable correspondence to the standard version.
Conclusions: We have proposed country-specific modifications to the original scoring protocol of the NEWS/NEWS-A that enhance inter-country comparability. These modifications have yielded sufficiently equivalent measurement models of the NEWS/NEWS-A. Some inter-country discrepancies remain. These need to be considered when interpreting findings from different countries.

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Background : The effects of the built environment on walking in seniors have not been studied in an Asian context. To examine these effects, valid and reliable measures are needed. The aim of this study was to develop and validate a questionnaire of perceived neighborhood characteristics related to walking appropriate for Chinese seniors (Neighborhood Environment Walkability Scale for Chinese Seniors, NEWS-CS). It was based on the Neighborhood Environment Walkability Scale - Abbreviated (NEWS-A), a validated measure of perceived built environment developed in the USA for adults. A secondary study aim was to establish the generalizability of the NEWS-A to an Asian high-density urban context and a different age group.

Methods : A multidisciplinary panel of experts adapted the original NEWS-A to reflect the built environment of Hong Kong and needs of seniors. The translated instrument was pre-tested on a sample of 50 Chinese-speaking senior residents (65+ years). The final version of the NEWS-CS was interviewer-administered to 484 seniors residing in four selected Hong Kong districts varying in walkability and socio-economic status. Ninety-two participants completed the questionnaire on two separate occasions, 2-3 weeks apart. Test-rest reliability indices were estimated for each item and subscale of the NEWS-CS. Confirmatory factor analysis was used to develop the measurement model of the NEWS-CS and cross-validate that of the NEWS-A.

Results : The final version of the NEWS-CS consisted of 14 subscales and four single items (76 items). Test-retest reliability was moderate to good (ICC > 50 or % agreement > 60) except for four items measuring distance to destinations. The originally-proposed measurement models of the NEWS-A and NEWS-CS required 2-3 theoretically-justifiable modifications to fit the data well.

Conclusions : The NEWS-CS possesses sufficient levels of reliability and factorial validity to be used for measuring perceived neighborhood environment in Chinese seniors. Further work is needed to assess its construct validity and generalizability to other Asian locations. In general, the measurement model of the original NEWS-A was generalizable to this study context, supporting the feasibility of cross-country and age-group comparisons of the effect of the neighborhood environment on walking using the NEWS-A as a tool to measure the perceived built environment.

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Background : The Neighborhood Environment Walkability Scale (NEWS) and its abbreviated form (NEWS-A) assess perceived environmental attributes believed to influence physical activity. A multilevel confirmatory factor analysis (MCFA) conducted on a sample from Seattle, WA showed that, at the respondent level, the factor-analyzable items of the NEWS and NEWS-A measured 11 and 10 constructs of perceived neighborhood environment, respectively. At the census blockgroup (used by the US Census Bureau as a subunit of census tracts) level, the MCFA yielded five factors for both NEWS and NEWS-A. The aim of this study was to cross-validate the individual- and blockgroup-level measurement models of the NEWS and NEWS-A in a geographical location and population different from those used in the original validation study.

Methods : A sample of 912 adults was recruited from 16 selected neighborhoods (116 census blockgroups) in the Baltimore, MD region. Neighborhoods were stratified according to their socio-economic status and transport-related walkability level measured using Geographic Information Systems. Participants self-completed the NEWS. MCFA was used to cross-validate the individual- and blockgroup-level measurement models of the NEWS and NEWS-A.

Results : The data provided sufficient support for the factorial validity of the original individual-level measurement models, which consisted of 11 (NEWS) and 10 (NEWS-A) correlated factors. The original blockgroup-level measurement model of the NEWS and NEWS-A showed poor fit to the data and required substantial modifications. These included the combining of aspects of building aesthetics with safety from crime into one factor; the separation of natural aesthetics and building aesthetics into two factors; and for the NEWS-A, the separation of presence of sidewalks/walking routes from other infrastructure for walking.

Conclusion : This study provided support for the generalizability of the individual-level measurement models of the NEWS and NEWS-A to different urban geographical locations in the USA. It is recommended that the NEWS and NEWS-A be scored according to their individual-level measurement models, which are relatively stable and correspond to constructs commonly used in the urban planning and transportation fields. However, prior to using these instruments in international and multi-cultural studies, further validation work across diverse non-English speaking countries and populations is needed.

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Purpose : The aim of this study was to examine the factorial and criterion validity of the Neighborhood Environment Walkability Scale (NEWS) and to develop an abbreviated version (NEWS-A).

Methods : A stratified two-stage cluster sample design was used to recruit 1286 adults. The sample was drawn from residential addresses within eight high- and eight low-walkable neighborhoods matched for socioeconomic status. Subjects completed the NEWS and reported weekly minutes of walking for transport and recreation using items from the International Physical Activity Questionnaire.

Results : Multilevel confirmatory factor analysis was used to develop measurement models of the NEWS and NEWS-A. Six individual-level and five blockgroup-level factors were identified. Factors/scales gauging presence of diversity of destinations, residential density, walking infrastructure, aesthetics, traffic safety, and crime were positively related to walking for transport. Aesthetics, mixed destinations, and residential density were associated with walking for recreation.

Conclusions : The NEWS and NEWS-A possess adequate levels of factorial and criterion validity. Alternative methods of scoring for different purposes are presented.

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Research in conditioning (all the processes of preparation for competition) has used group research designs, where multiple athletes are observed at one or more points in time. However, empirical reports of large inter-individual differences in response to conditioning regimens suggest that applied conditioning research would greatly benefit from single-subject research designs. Single-subject research designs allow us to find out the extent to which a specific conditioning regimen works for a specific athlete, as opposed to the average athlete, who is the focal point of group research designs. The aim of the following review is to outline the strategies and procedures of single-subject research as they pertain to the assessment of conditioning for individual athletes. The four main experimental designs in single-subject research are: the AB design, reversal (withdrawal) designs and their extensions, multiple baseline designs and alternating treatment designs. Visual and statistical analyses commonly used to analyse single-subject data, and advantages and limitations are discussed. Modelling of multivariate single-subject data using techniques such as dynamic factor analysis and structural equation modelling may identify individualised models of conditioning leading to better prediction of performance. Despite problems associated with data analyses in single-subject research (e.g. serial dependency), sports scientists should use single-subject research designs in applied conditioning research to understand how well an intervention (e.g. a training method) works and to predict performance for a particular athlete.

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Background:
Achieving optimal outcomes in type 2 diabetes (T2DM) involves several demanding self-care 
behaviours, e.g. managing diet, activity, medications, monitoring glucose levels, footcare. The Self-Care Inventory-Revised (SCI-R) is valid for use in people with T2DM in the US. Our aim was to determine its suitability for use in the UK.

Methods:
353 people with T2DM participated in the AT.LANTUS Follow-on study, completing measures of diabetes self-care (SCI-R), generic and diabetes-specific well-being (W- BQ28), and diabetes treatment satisfaction (DTSQ). Statistical analyses were conducted to explore structure, reliability, and validity of the SCI-R.
Results:
Principal components analysis indicated a 13-item scale (items loading >0.39) with satisfactory internal consistency reliability (α = 0.77), although neither this model nor any alternatives were confirmed in the confirmatory factor analysis. Acceptability was high (>95% completion for all but one item); ceiling effects were demonstrated for six items. As expected, convergent validity (correlations between self-care behaviours) was found for few items. Divergent validity was supported by expected low correlations between SCI-R total and well-being (rs = 0.02-0.21) and treatment satisfaction (rs = 0.29). Known-groups validity was partially supported with significant differences in SCI-R total by HbA1c (≤7.5% (58 mmol/mol): 72 ± 11, >7.5% (58 mmol/mol): 68 ± 14, p < 0.05) and diabetes duration (≤16 years: 67 ± 13, >16 years: 71 ± 12, p < 0.001) but not by presence/absence of complications or by insulin treatment algorithm.
Conclusions:
The SCI-R is a brief, valid and reliable measure of self-care in people with T2DM in the UK. However, ceiling effects raise concerns about its potential for responsiveness in clinical trials. Individual items may be more useful clinically than the total score.

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Public attitudes towards sex offenders are believed to play a key role in the development of legislation and public policy designed to manage the risks posed by known sex offenders who live in the community. There have, however, been few previous attempts to validate methods by which public attitudes can be measured. The current study aims to address this issue by establishing the factor structure of the Community Attitudes Towards Sex Offenders (CATSO) scale with an Australian community sample and examine the extent to which demographic variables and support for sex offender management policies influence these attitudes. A sample of 552 participants recruited through online social media sites completed the CATSO as well as a number of items developed by the researchers designed to assess individuals’ support for specific sex offender policies. Results of an exploratory factor analysis suggested the presence of four distinct factors which were labelled ‘social tendencies’, ‘treatment and punishment’, ‘crime characteristics’ and ‘sexual behaviour’. Individuals with higher levels of educational attainment rated sex offenders less negatively than those with lower educational attainment, while those who reported being supportive of community notification reported more negative attitudes towards sex offenders.

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Objectives
To assess the contribution of back-translation and expert committee to the content and psychometric properties of a translated multidimensional questionnaire.

Study Design and Setting
Recommendations for questionnaire translation include back-translation and expert committee, but their contribution to measurement properties is unknown. Four English to French translations of the Health Education Impact Questionnaire were generated with and without committee or back-translation. Face validity, acceptability, and structural properties were compared after random assignment to people with rheumatoid arthritis (N = 1,168), chronic renal failure (N = 2,368), and diabetes (N = 538). For face validity, 15 bilingual people compared translations quality with the original. Psychometric properties were examined using confirmatory factor analysis (metric and scalar invariance) and item response theory.

Results
Qualitatively, there were five types of translation errors: style, intensity, frequency/time frame, breadth, and meaning. Bilingual assessors ranked best the translations with committee (P = 0.0026). All translations had good structural properties (root mean square error of approximation <0.05; comparative fit index [CFI], ≥0.899; and Tucker–Lewis index, ≥0.889). Full measurement invariance was observed between translations (ΔCFI ≤ 0.01) with metric invariance between translations and original (lowest ΔCFI = 0.022 between fully constrained models and models with free intercepts). Item characteristic curve analyses revealed no significant differences.

Conclusion
This is the first experimental evidence that back-translation has moderate impact, whereas expert committee helps to ensure accurate content.

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The significant divergence between the retention of 16 terpene standards on porous graphitized carbon (PGC) and C18 packing materials are illustrated. The PGC surface is shown to provide a selectivity toward shape, polarity, and structure that is not afforded by the C18 surface. This observation is illustrated by plots of the retention factors similar to those typically used to represent 2D-HPLC separations. A geometric approach to factor analysis was used to measure the separation divergence together with the selectivity and the product selectivity factors of closely related species. When a methanol mobile phase was used with the PGC surface, a large fraction of the separation space could be utilized. That is further reflected by a spreading angle of 80.3°. The PGC material was also successful at resolving structural isomers where the C18 phase was not. It was also found that the choice of the mobile phase is important when using this material. A much larger degree of space utilization was seen with methanol than with acetonitrile that displayed a spreading angle of only 40.8°.

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To achieve the greatest peak capacity in two-dimensional high performance liquid chromatography (2D-HPLC) a gradient should be operated in both separation dimensions. However, it is known that when an injection solvent that is stronger than the initial mobile phase composition is deleterious to peak performance, thus causing problems when cutting a portion from one gradient into another. This was overcome when coupling hydrophilic interaction with reversed phase chromatography by introducing a counter gradient that changed the solvent strength of the second dimension injection. It was found that an injection solvent composition of 20% acetonitrile in water gave acceptable results in one-dimensional simulations with an initial composition of 5% acetonitrile. When this was transferred to a 2D-HPLC separation of standards it was found that a marked improvement in peak shape was gained for the moderately retained analytes (phenol and dimethyl phthalate), some improvement for the weakly retained caffeine and very little change for the strongly retained n-propylbenzene and anthracene which already displayed good chromatographic profiles. This effect was transferred when applied to a 2D-HPLC separation of a coffee extract where the indecipherable retention profile was transformed to a successful application multidimensional chromatography with peaks occupying 71% of the separation space according to the geometric approach to factor analysis.

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Involvement in meal preparation and eating meals with the family are associated with better dietary patterns in adolescents, however little research has included older children or longitudinal study designs. This 3-year longitudinal study examines cross-sectional and longitudinal associations between family food involvement, family dinner meal frequency and dietary patterns during late childhood. Questionnaires were completed by parents of 188 children from Greater Melbourne, Australia at baseline in 2002 (mean age = 11.25 years) and at follow-up in 2006 (mean age = 14.16 years). Principal components analysis (PCA) was used to identify dietary patterns. Factor analysis (FA) was used to determine the principal factors from six indicators of family food involvement. Multiple linear regression models were used to predict the dietary patterns of children and adolescents at baseline and at follow-up, 3 years later, from baseline indicators of family food involvement and frequency of family dinner meals. PCA revealed two dietary patterns, labeled a healthful pattern and an energy-dense pattern. FA revealed one factor for family food involvement. Cross-sectionally among boys, family food involvement score (β = 0.55, 95% CI: 0.02, 1.07) and eating family dinner meals daily (β = 1.11, 95% CI: 0.27, 1.96) during late childhood were positively associated with the healthful pattern. Eating family dinner meals daily was inversely associated with the energy-dense pattern, cross-sectionally among boys (β = −0.56, 95% CI: −1.06, −0.06). No significant cross-sectional associations were found among girls and no significant longitudinal associations were found for either gender. Involvement in family food and eating dinner with the family during late childhood may have a positive influence on dietary patterns of boys. No evidence was found to suggest the effects on dietary patterns persist into adolescence.

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Few studies have investigated whether parents’, teachers’ and children’s responses to the strengths and difficulties questionnaire (SDQ) have equivalence. In this study, data from 854 matched questionnaires collected in Malaysia were subjected to tau equivalence confirmatory factor analysis, to assess if all three groups responded to the same target (the child) similarly. We first fitted Goodman’s (Journal of Child Psychology and Psychiatry, 38, 581–586, (1997a); Journal of Child Psychology and Psychiatry, 40, 791–801, 1997b) five factor model, but found that this did not fit the model despite attempts to improve and rectify model fit. We thereafter attempted to fit Dickey and Blumberg (Journal of the American Academy of Child Adolescent Psychiatry, 43, 1159–1167, 2004) three factor model, but similarly found a lack of fit. We then undertook an exploratory model with a random half of the data, obtaining a three factor solution, and tested this in a confirmatory tau equivalence model. The Unconstrained Model provided a fit to the data, revealing a similar structure across the three informant groups. As this fit was for the Unconstrained Model, it reveals that groups differ in the value they place on each of the variables but overall that held a similar underlying factor structure. The findings are discussed in relation to the possible cultural issues involved and the use of the SDQ.

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This paper reports pilot data from an instrument devised as part of a large ARC funded project that aims, among other things, to investigate factors that influence the decisions of students in rural and/or disadvantaged areas to continue their schooling beyond Year 10. One section of the pilot student questionnaire comprised 42 items designed to reflect dimensions believed to influence these decisions. Participants responded on 5-point Likert scales indicating the extent of their agreement from Strongly Disagree to Strongly Agree with each of the items. We were interested in the extent to which the data supported the theoretical structure that underpinned the structure of the questionnaire and in testing the appropriateness of the language used. The large scale data collection will survey students from Years 5 to 11 with as few adaptations for differences in literacy levels across that range as possible. To this end, the pilot questionnaire was administered to Year 5 (n = 44) and Year 9/10 students (n = 50) with identical wording for both grade levels. A factor analysis of the complete data set (n = 94) provided initial evidence that being happy at school; having family support to continue with education, and appropriate curriculum options and extra-curricular activities, perceiving oneself as a high achiever both in general and in relation to mathematics, having teacher and peer support to continue, being positive about English, planning to be an apprentice, and having a job type in mind are dimensions worthy of further exploration in the larger study.

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Studies conducted in community samples suggest that psychotic-like experiences are common in the general population, leading to suggestions that they are either variations of normal personality or are different expressions of underlying vulnerability to psychotic disorder. Different types of psychotic symptoms may exist, some being normal variants and some having implications for mental health and functioning. The aim of the present study was to determine if different subtypes of psychotic-like experiences could be identified in a community sample of adolescents and to investigate if particular subtypes were more likely to be associated with psychosocial difficulties, that is, distress, depression and poor functioning, than other subtypes. Eight hundred and seventy-five Year 10 students from 34 schools participated in a cross-sectional survey that measured psychotic-like experiences using the Community Assessment of Psychic Experiences; depression using the Centre for Epidemiologic Studies Depression Scale; and psychosocial functioning using the Revised Multidimensional Assessment of Functioning Scale. Factor analysis was conducted to identify any subtypes of psychotic experiences. Four subtypes of psychotic-like experiences were identified: Bizarre Experiences, Perceptual Abnormalities, Persecutory Ideas, and Magical Thinking. Intermittent, infrequent psychotic experiences were common, but frequent experiences were not. Bizarre Experiences, Perceptual Abnormalities and Persecutory Ideas were strongly associated with distress, depression and poor functioning. Magical Thinking was only weakly associated with these variables. Overall these findings may suggest that infrequent psychotic-like experiences are unlikely to be a specific risk factor for onset of a psychotic disorder in community samples. Given that the different subtypes had varying associations with current difficulties it is suggested that not all subtypes confer the same risk for onset of psychotic disorder and poor outcome. Bizarre Experiences, Perceptual Abnormalities and Persecutory Ideas may represent expressions of underlying vulnerability to psychotic disorder, but Magical Thinking may be a normal personality variant.