Random assignment of intervention points in two phase single-case designs: data-division-specific distributions

The present study explores the statistical properties of a randomization test based on the random assignment of the intervention point in a two-phase (AB) single-case design. The focus is on randomization distributions constructed with the values of the test statistic for all possible random assignments and used to obtain p-values. The shape of those distributions is investigated for each specific data division defined by the moment in which the intervention is introduced. Another aim of the study consisted in testing the detection of inexistent effects (i.e., production of false alarms) in autocorrelated data series, in which the assumption of exchangeability between observations may be untenable. In this way, it was possible to compare nominal and empirical Type I error rates in order to obtain evidence on the statistical validity of the randomization test for each individual data division. The results suggest that when either of the two phases has considerably less measurement times, Type I errors may be too probable and, hence, the decision making process to be carried out by applied researchers may be jeopardized.

Development of an instrument to assess Human Resource Quality (HRQ) and measuring the impact of TQM efforts on HRQ using the instrument

This research is aimed at developing an instrument for measuring human resource quality in organizations. The researcher has developed the instrument for measuring HRQ based on extensive literature survey and expert opinion. Statistical validity of the Instrument has also been established. This instrument was used to measure the changes in Human Resource Quality in selected organizations wherein quality management practices are being implemented. Data collected was analyzed and presented in this thesis. It has been found that there are significant changes in all the indicators of Human Resource Quality. There is improvement in Cultural Change Index(CCI), Quality of Work Life Index(QWLI) and Employee Satisfaction Index(ESI). The Human Resource Quality index has also increased significantly in all the organizations. It has been observed from the study that implementation of TQM leads to significant changes in Human Resource Quality. This instrument is capable of measuring minor variations in each indicator of HRQ and can be used to identify areas of weakness and strength in the case of Human Resource Quality. The instrument can further be modified by future research. This research work provided excellent opportunities for the researcher for self-development and has made him confident to undertake such activities for the benefit of the learning community.

Coledocolitiasis gigante, factores predictores de éxito, fracaso del manejo endosópico. Hospital de la Samaritana 2009-2011

La prevalencia de coledocolitiasis es de un 10 a 20%. 10-20% tienen coledocolitiasis gigante, es decir presencia de cálculos mayores de 15 mm, aumentando la morbimortalidad por complicaciones. El objetivo principal fue determinar la frecuencia de coledocolitiasis gigante, la presencia de factores predictores del éxito o fracaso del manejo endoscópico. El éxito en el manejo endoscópico está entre 80 y 90%, un 20% requieren cirugía de exploración biliar. Se realizó la búsqueda de las variables utilizando el instrumento para la recolección de la información. Se realizó un análisis univariado y bivariado de las variables medidas y se utilizo STATA versión 10. Como principal resultado, se encontró que la frecuencia de coledocolitiasis gigante en nuestra población fue del 10%, el éxito del manejo endoscopio fue del 89.23% y el factor predictor mas fuerte para el éxito fue el diámetro del cálculo, siendo mayor para cálculos de menos de 19.09 mm. Como conclusión, en nuestro estudio, la frecuencia de coledocolitiasis gigante es cercana a la conocida en la literatura mundial. El manejo endoscópico en nuestro estudio es el pilar en estos casos, teniendo probabilidad de éxito en el manejo que es igual a la publicada en los estudios mundiales, que existe la probabilidad que el tamaño del cálculo mayor a 19 mm de diámetro indique mayor tasa de fracaso y requerimiento de técnicas endoscópicas avanzadas para su éxito. Se requieren estudios, con mayor número de pacientes para determinar la validez estadística de estos resultados.

Methods of Regularities Searching Based on Optimal Partitioning

The purpose of discussed optimal valid partitioning (OVP) methods is uncovering of ordinal or continuous explanatory variables effect on outcome variables of different types. The OVP approach is based on searching partitions of explanatory variables space that in the best way separate observations with different levels of outcomes. Partitions of single variables ranges or two-dimensional admissible areas for pairs of variables are searched inside corresponding families. Statistical validity associated with revealed regularities is estimated with the help of permutation test repeating search of optimal partition for each permuted dataset. Method for output regularities selection is discussed that is based on validity evaluating with the help of two types of permutation tests.

Evaluation of the internal structural validity of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) anxiety disorders in children and adolescents

The purpose of the present dissertation was to evaluate the internal validity of symptoms of four common anxiety disorders included in the Diagnostic and Statistical Manual of Mental Disorders fourth edition (text revision) (DSM-IV-TR; American Psychiatric Association, 2000), namely, separation anxiety disorder (SAD), social phobia (SOP), specific phobia (SP), and generalized anxiety disorder (GAD), in a sample of 625 youth (ages 6 to 17 years) referred to an anxiety disorders clinic and 479 parents. Confirmatory factor analyses (CFAs) were conducted on the dichotomous items of the SAD, SOP, SP, and GAD sections of the youth and parent versions of the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV: C/P; Silverman & Albano, 1996) to test and compare a number of factor models including a factor model based on the DSM. Contrary to predictions, findings from CFAs showed that a correlated model with five factors of SAD, SOP, SP, GAD worry, and GAD somatic distress, provided the best fit of the youth data as well as the parent data. Multiple group CFAs supported the metric invariance of the correlated five factor model across boys and girls. Thus, the present study’s finding supports the internal validity of DSM-IV SAD, SOP, and SP, but raises doubt regarding the internal validity of GAD.^

Reproducibility, reliability and validity of measurements obtained from Cecile3 digital models

The aim of this study was to determine the reproducibility, reliability and validity of measurements in digital models compared to plaster models. Fifteen pairs of plaster models were obtained from orthodontic patients with permanent dentition before treatment. These were digitized to be evaluated with the program Cécile3 v2.554.2 beta. Two examiners measured three times the mesiodistal width of all the teeth present, intercanine, interpremolar and intermolar distances, overjet and overbite. The plaster models were measured using a digital vernier. The t-Student test for paired samples and interclass correlation coefficient (ICC) were used for statistical analysis. The ICC of the digital models were 0.84 ± 0.15 (intra-examiner) and 0.80 ± 0.19 (inter-examiner). The average mean difference of the digital models was 0.23 ± 0.14 and 0.24 ± 0.11 for each examiner, respectively. When the two types of measurements were compared, the values obtained from the digital models were lower than those obtained from the plaster models (p < 0.05), although the differences were considered clinically insignificant (differences < 0.1 mm). The Cécile digital models are a clinically acceptable alternative for use in Orthodontics.

Cross-cultural Adaptation, Reliability and Validity of the DAFS-R in a Sample of Brazilian Older Adults

The Direct Assessment of Functional Status-Revised (DAFS-R) is an instrument developed to objectively measure functional capacities required for independent living. The objective of this study was to translate and culturally adapt the DAFS-R for Brazilian Portuguese (DAFS-BR) and to evaluate its reliability and validity. The DAFS-BR was administered to 89 older patients classified previously as normal controls, mild cognitive impairment (MCI) and Alzheimer`s disease (AD). The results indicated good internal consistency (Cronbach`s alpha = 0.78) in the total sample. The DAFS-BR showed high interobserver reliability (0.996; p < .001) as well as test-retest stability over 1-week interval (0.995; p < .001). Correlation between the DAFS-BR total score and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) was moderate and significant (r = -.65, p < .001) in the total sample, whereas it did not reach statistical significance within each diagnostic group. Receiver operating characteristic curve analyses suggested that DAFS-BR has good sensitivity and specificity to identify MCI and AD. Results suggest that DAFS-BR can document degrees of severity of functional impairment among Brazilian older adults.

RELIABILITY AND VALIDITY OF THE PHOTOGRAMMETRY FOR SCOLIOSIS EVALUATION: A CROSS-SECTIONAL PROSPECTIVE STUDY

Objective: The purpose of this study was to investigate the reliability and validity of photogrammetry in measuring the lateral spinal inclination angles. Methods: Forty subjects (32 female and 8 males) with a mean age of 23.4 +/- 11.2 years had their scoliosis evaluated by radiographs of their trunk, determined by the Cobb angle method, and by photogrammetry. The statistical methods used included Cronbach alpha, Pearson/Spearman correlation coefficients, and regression analyses. Results: The Cronbach a values showed that the photogrammetric measures showed high internal consistency, which indicated that the sample was bias free. The radiograph method showed to be more precise with intrarater reliabilities of 0.936, 0.975, and 0.945 for the thoracic, lumbar, and thoracolumbar curves, respectively, and interrater reliabilities of 0.942 and 0.879 for the angular measures of the thoracic and thoracolumbar segments, respectively. The regression analyses revealed a high determination coefficient although limited to the adjusted linear model between the radiographic and photographic measures. It was found that with more severe scoliosis, the lateral curve measures obtained with the photogrammetry were for the thoracic and lumbar regions (R = 0.619 and 0.551). Conclusions: The photogrammetric measures were found to be reproducible in this study and could be used as Supplementary information to decrease the number of radiographs necessary for the monitoring of scoliosis. (J Manipulative Physiol Ther 2009;32:423-430)

Clinical Validity of the Protocol for Multi-Professional Centers for the Determination of Signs and Symptoms of Temporomandibular Disorders. Part II

The aims of this study were to analyze the criterion and construct validity of Part II of the protocol for multi-professional centers for the determination of signs and symptoms of temporomandibular disorders (ProTMDMulti) as a measure of TMD severity. The study was conducted on eight asymptomatic subjects (CG) and 30 subjects with articular TMD (TMDG), according to the Research Diagnostic Criteria for TMD (RDC/TMD). The ProTMDMulti-Part II was validated using the Helkimo Clinical Dysfunction Index (Di). The construct validity was tested using the analysis of the ability of ProTMDMulti-part II to differentiate the CG from the TMDG and to measure the changes that occurred in the TMDG between the period before and after TMD treatment. Correlations between the Di and the ProTMDMulti-Part II scores were calculated using the Spearman test. Inter- and intragroup comparisons were made (p<0.05). There was a statistically significant correlation between the Helkimo Clinical Dysfunction Index (Di) and the severity scores of the ProTMDMulti-Part II. There was a significant difference between TMDG and CG regarding the severity of signs and symptoms. The present study provides statistical evidence of the clinical validity of the ProTMDmulti-Part II as a measure of the severity of TMD symptoms.

The validity and heritability of self-report osteoarthritis in an Australian older twin sample

In order to investigate the genetic and environmental antecedents of osteoarthritis (CA), self-report measures of joint pain, stiffness and swelling were obtained from a population-based sample of 1242 twin pairs over 50 years of age. In order to provide validation for these self-report measures, a subsample of 118 twin pairs were examined according to the American College of Rheumatology clinical and radiographic criteria for the classification of osteoarthritis. A variety of statistical methods were employed to identify the model derived from self-report variables which would provide optimal prediction of these standardised assessments, and structural equation modelling was used to determine the relative influences of genetic and environmental influences on the development of osteoarthritis. Significant genetic effects were found to contribute to osteoarthritis of the hands, hips and knees in women, with heritability estimates ranging from 30-46% depending on the site. In addition, the additive genetic effects contributing to osteoarthritis in various parts of the body were confirmed to be the same. Statistically significant familial aggregation of osteoarthritis in men was also observed, but it was not possible to determine whether this was due to genetic or shared environmental effects.

Factorial validity of the Maslach Burnout Inventory (MBI-HSS) among Spanish professionals

OBJECTIVE: To assess the factorial validity and internal consistency of the Maslach Burnout Inventory (MBI-HSS). METHODS: In a sample consisting of 705 Spanish professionals from diverse occupational sectors (health, education, police and so one), seven plausible factorial models hypothesized were compared using LISREL 8. RESULTS: The four-factor oblique solution and the three-factor oblique solution showed the best and similar fit. Deletion of Item 12 and Item 16, taking into consideration the suggestions in the manual, improved the goodness of fit for both models. The four-factor oblique model suggests that, in addition to Emotional Exhaustion (EE) and Depersonalization (DP), Personal Accomplishment (PA) consists of two components labeled here Self-Competence (Items 4, 7, 17, and 21) and the Existential Component (Items 9, 12, 18, and 19). However, the alpha coefficient was relatively low for the Self-Competence component, suggesting that it is more suitable to estimate the syndrome as a threedimensional construct. The Cronbach's alpha was satisfactory for PA (alpha =.71) and EE (alpha =.85), and moderate for DP (alpha =.58). CONCLUSIONS: The results show that the MBI-HSS offers factorial validity and its scales present internal consistency to evaluate the quality of working life for Spanish professionals.

Cross-cultural validity of the demand-control questionnaire: Swedish and Brazilian workers

OBJECTIVE To evaluate the cross-cultural validity of the Demand-Control Questionnaire, comparing the original Swedish questionnaire with the Brazilian version. METHODS We compared data from 362 Swedish and 399 Brazilian health workers. Confirmatory and exploratory factor analyses were performed to test structural validity, using the robust weighted least squares mean and variance-adjusted (WLSMV) estimator. Construct validity, using hypotheses testing, was evaluated through the inspection of the mean score distribution of the scale dimensions according to sociodemographic and social support at work variables. RESULTS The confirmatory and exploratory factor analyses supported the instrument in three dimensions (for Swedish and Brazilians): psychological demands, skill discretion and decision authority. The best-fit model was achieved by including an error correlation between work fast and work intensely (psychological demands) and removing the item repetitive work (skill discretion). Hypotheses testing showed that workers with university degree had higher scores on skill discretion and decision authority and those with high levels of Social Support at Work had lower scores on psychological demands and higher scores on decision authority. CONCLUSIONS The results supported the equivalent dimensional structures across the two culturally different work contexts. Skill discretion and decision authority formed two distinct dimensions and the item repetitive work should be removed.

Validity and reliability of a health care service evaluation instrument for tuberculosis

OBJECTIVE To evaluate the validity and reliability of an instrument that evaluates the structure of primary health care units for the treatment of tuberculosis.METHODS This cross-sectional study used simple random sampling and evaluated 1,037 health care professionals from five Brazilian municipalities (Natal, state of Rio Grande do Norte; Cabedelo, state of Paraíba; Foz do Iguaçu, state of Parana; Sao José do Rio Preto, state of Sao Paulo, and Uberaba, state of Minas Gerais) in 2011. Structural indicators were identified and validated, considering different methods of organization of the health care system in the municipalities of different population sizes. Each structure represented the organization of health care services and contained the resources available for the execution of health care services: physical resources (equipment, consumables, and facilities); human resources (number and qualification); and resources for maintenance of the existing infrastructure and technology (deemed as the organization of health care services). The statistical analyses used in the validation process included reliability analysis, exploratory factor analysis, and confirmatory factor analysis.RESULTS The validation process indicated the retention of five factors, with 85.9% of the total variance explained, internal consistency between 0.6460 and 0.7802, and quality of fit of the confirmatory factor analysis of 0.995 using the goodness-of-fit index. The retained factors comprised five structural indicators: professionals involved in the care of tuberculosis patients, training, access to recording instruments, availability of supplies, and coordination of health care services with other levels of care. Availability of supplies had the best performance and the lowest coefficient of variation among the services evaluated. The indicators of assessment of human resources and coordination with other levels of care had satisfactory performance, but the latter showed the highest coefficient of variation. The performance of the indicators “training” and “access to recording instruments” was inferior to that of other indicators.CONCLUSIONS The instrument showed feasibility of application and potential to assess the structure of primary health care units for the treatment of tuberculosis.

Study of the Reliability of Statistical Timing Analysis for Real-Time Systems

Presented at 23rd International Conference on Real-Time Networks and Systems (RTNS 2015). 4 to 6, Nov, 2015, Main Track. Lille, France.

Statistical tests for scaling in the inter-event times of earthquakes in California

We explore in depth the validity of a recently proposed scaling law for earthquake inter-event time distributions in the case of the Southern California, using the waveform cross-correlation catalog of Shearer et al. Two statistical tests are used: on the one hand, the standard two-sample Kolmogorov-Smirnov test is in agreement with the scaling of the distributions. On the other hand, the one-sample Kolmogorov-Smirnov statistic complemented with Monte Carlo simulation of the inter-event times, as done by Clauset et al., supports the validity of the gamma distribution as a simple model of the scaling function appearing on the scaling law, for rescaled inter-event times above 0.01, except for the largest data set (magnitude greater than 2). A discussion of these results is provided.