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Valid Instruments (valid + instruments)
Selected AbstractsChoosing the Number of InstrumentsECONOMETRICA, Issue 5 2001Stephen G. Donald Properties of instrumental variable estimators are sensitive to the choice of valid instruments, even in large cross-section applications. In this paper we address this problem by deriving simple mean-square error criteria that can be minimized to choose the instrument set. We develop these criteria for two-stage least squares (2SLS), limited information maximum likelihood (LIML), and a bias adjusted version of 2SLS (B2SLS). We give a theoretical derivation of the mean-square error and show optimality. In Monte Carlo experiments we find that the instrument choice generally yields an improvement in performance. Also, in the Angrist and Krueger (1991) returns to education application, when the instrument set is chosen in the way we consider, it turns out that both 2SLS and LIML give similar (large) returns to education. [source] The Norwegian version of the American pain society patient outcome questionnaire: reliability and validity of three subscalesJOURNAL OF CLINICAL NURSING, Issue 15 2008Alfhild Dihle MSc Aims and objectives., To examine some psychometric properties of the Norwegian version of the American Pain Society's Patient Outcome Questionnaire (APS-POQ-N). Background., This study is part of an investigation of Norwegian orthopaedic surgical patients, where the overall aim is to evaluate the quality of postoperative pain management. Therefore, an adequate questionnaire on the quality of postoperative pain management was needed. Methods., The sample included 114 orthopaedic postoperative patients. The instrument consists of three main subscales, namely the modified Brief Pain Inventory (modified BPI subscale), the subscale on satisfaction with pain management (Satisfaction subscale) and the subscale on beliefs about pain management (Beliefs subscale), together with six single items about pain management. The reliability of these three main subscales was estimated using Cronbach's alpha coefficients and the construct validity was evaluated using principal-axis factor analysis with oblimin rotation. Results., Face and content validity of the APS-POQ-N were satisfactory, while the modified BPI and the Beliefs subscales showed acceptable internal consistency but the Satisfaction subscale did not. Factor analyses yielded a three-factor solution for the modified BPI, a one-factor solution for the Satisfaction subscale and a two-factor solution for the Beliefs subscale. Conclusions., The APS-POQ-N appears, in general, to be an acceptable method of evaluating postoperative pain management in orthopaedic postoperative patients. However, the alpha value of the Satisfaction subscale was low, and thus the subscale is not recommended for this purpose. Relevance to clinical practice., Reliable and valid instruments are important when performing clinical research. This instrument is applicable as an indicator of quality of postoperative pain management in clinical practice and research. [source] Validation of the short forms of the incontinence impact questionnaire (IIQ-7) and the urogenital distress inventory (UDI-6) in a Turkish population,NEUROUROLOGY AND URODYNAMICS, Issue 1 2007Cetin Cam Abstract Aim To validate the Turkish versions of the IIQ-7 and UDI-6 for use in Turkish-speaking populations. Methods After establishing the test-retest reliability and internal consistency in a pilot study, 302 patients were enrolled in the study and general and subscale scores of the questionnaires were calculated. All participants underwent an urodynamic assessment. Results Both instruments showed a high internal consistency (Cronbach's alpha for the IIQ-7 and UDI-6 was 0.87 and 0.74, respectively) and test-retest reliability (Spearman's rho was 0.99 for both of the scales (P,<,0.001). 55.6% of the participants showed urodynamic abnormality and/or leakage. 39.7% had urodynamic stress incontinence (USI) and 15.9% had detrussor overactivity (DOA),±,USI. The mean scores of each IIQ-7 and UDI-6 were significantly higher in the USI, and DOA,±,USI groups compared with normal women. Women with DOA,±,USI scored highest in the IIQ-7 and UDI-6. The irritative subscale scores of the 1st and 2nd items of the UDI-6 were significantly higher in the DOA,±,USI group. The stress subscale scores of 3rd and 4th items of UDI-6 were significantly higher in the USI group. Women with postvoid residual (PVR) urine values greater than 50 ml had significantly higher obstructive subscale scores compared to the ones who had less residual volumes. Conclusions The Turkish translated versions of the IIQ-7 and UDI-6 are reliable, consistent and valid instruments for assessing symptom severity and the impact on QOL in Turkish speaking women with urinary incontinence. Neurourol. Urodynam. © 2006 Wiley-Liss, Inc. [source] Cross-cultural Adaptation and Validation of the Chinese Voice Handicap Index-10THE LARYNGOSCOPE, Issue 7 2006Paul K. Y. Lam FRCSEd Abstract Objectives/Hypothesis: Recent developments in voice assessment propose the use of quality of life measurements. The Voice Handicap Index (VHI) is one of the most psychometrically robust and well-studied instruments among the various instruments for measuring quality of life. Two versions of VHI (VHI-30 and VHI-10) have been shown to be valid instruments for distinguishing dysphonic from nondysphonic individuals and also for documenting treatment effect for dysphonic patients. The VHI has been used worldwide; however, the psychometric properties of the Chinese version of VHI remains untested. This study aimed to investigate such properties of the Chinese VHI-30 and VHI-10 in the Hong Kong Chinese population. Study Design: Psychometric analysis of the Chinese VHI-30 and VHI-10 in dysphonic patients and control subjects. Methods: The original VHI-30 was translated into Chinese and was completed by 131 dysphonic patients and 54 nondysphonic individuals. The dysphonic patients also self-rated their dysphonic severity. Results: Results showed high test-retest reliability and high item-total correlation for both Chinese VHI-30 and VHI-10. Both Chinese versions could be used to distinguish different dysphonic groups and between dysphonic and nondysphonic groups. Significant correlation was found between the VHI scores and the patients' self-rated dysphonic severity. Conclusion: The present study supported the original three-factorial structures of the VHI-30 and the use of the VHI for the Chinese population. It is shown that the Chinese VHI-10 is a strong representation of VHI-30 and is recommended for use in clinics because of its validity and ease of use by patients. [source] Future research on dementia relating to culturally and linguistically diverse communitiesAUSTRALASIAN JOURNAL ON AGEING, Issue 3 2009Lee-Fay Low About one in five older Australians were born overseas. However, there has been very little information published in Australia or internationally about dementia in persons from culturally and linguistically diverse (CALD) backgrounds. This limits our ability to plan for and provide evidence-based medical care, social care and aged care services to persons from CALD backgrounds. This paper describes challenges to conducting CALD dementia research; these include sampling, having valid instruments and costs. Nine key research recommendations in the areas of epidemiology, community knowledge, carers, service delivery, screening and assessment, medical management, residential aged care and minority CALD reached by consensus by an expert group are presented. The paper closes with some strategies to encourage CALD research. The material presented here will provide guidance for future research endeavours. [source] | ||||||||||