Reliability Of Different Measures Research Articles

Natural mechanisms and artificial PEG-induced mechanism that repair traumatic damage to the plasmalemma in eukaryotes.

Eukaryotic tissues are composed of individual cells surrounded by a plasmalemma that consists of a phospholipid bilayer with hydrophobic heads that bind cell water. Bound-water creates a thermodynamic barrier that impedes the fusion of a plasmalemma with other membrane-bound intracellular structures or with the plasmalemma of adjacent cells. Plasmalemmal damage consisting of small or large holes or complete transections of a cell or axon results in calcium influx at the lesion site. Calcium activates fusogenic pathways that have been phylogenetically conserved and that lower thermodynamic barriers for fusion of membrane-bound structures. Calcium influx also activates phylogenetically conserved sealing mechanisms that mobilize the gradual accumulation and fusion of vesicles/membrane-bound structures that seal the damaged membrane. These naturally occurring sealing mechanisms for different cells vary based on the type of lesion, the type of cell, the proximity of intracellular membranous structures to the lesion and the relation to adjacent cells. The reliability of different measures to assess plasmalemmal sealing need be carefully considered for each cell type. Polyethylene glycol (PEG) bypasses calcium and naturally occurring fusogenic pathways to artificially fuse adjacent cells (PEG-fusion) or artificially seal transected axons (PEG-sealing). PEG-fusion techniques can also be used to rapidly rejoin the closely apposed, open ends of severed axons. PEG-fused axons do not (Wallerian) degenerate and PEG-fused nerve allografts are not immune-rejected, and enable behavioral recoveries not observed for any other clinical treatment. A better understanding of natural and artificial mechanisms that induce membrane fusion should provide better clinical treatment for many disorders involving plasmalemmal damage.

Reliability of Postural Sway Measures of Standing Balance Tasks.

The reliability of balance exercises performance in experimental and clinical studies has typically been confined to a small set of exercises. In order to advance the field of assessing balance exercise intensity, establishing the reliability of performance during a more diverse array of exercises should be undertaken. The purpose of this study was to investigate the test-retest reliability of postural sway produced during performance of 24 different balance tasks, and to evaluate the reliability of different measures of postural sway. Sixty-two healthy subjects between the ages of 18 and 85 years of age (50% female, mean age 55 ± 20 years) participated. Subjects were tested during two visits one week apart and performed two sets of the 24 randomized standing tasks per visit. The tasks consisted of combinations of the following factors: surface (firm and foam), vision (eyes open and eyes closed), stance (feet apart and semi-tandem), and head movement (no movement, yaw, and pitch). Angular position displacement, angular velocity, and linear acceleration postural sway in the pitch and roll planes was recorded via an inertial measurement unit. The postural sway measures demonstrated at fair to good test-retest reliability with few exceptions, and angular velocity measures demonstrated the greatest reliability. The between-visit reliability of two averaged trials was excellent for most tasks. The study indicates that performance of most balance tasks used as part of balance rehabilitation is reliable, and quantitative assessment could be used to document change.

Computerized Analysis of Verbal Fluency: Normative Data and the Effects of Repeated Testing, Simulated Malingering, and Traumatic Brain Injury.

In verbal fluency (VF) tests, subjects articulate words in a specified category during a short test period (typically 60 s). Verbal fluency tests are widely used to study language development and to evaluate memory retrieval in neuropsychiatric disorders. Performance is usually measured as the total number of correct words retrieved. Here, we describe the properties of a computerized VF (C-VF) test that tallies correct words and repetitions while providing additional lexical measures of word frequency, syllable count, and typicality. In addition, the C-VF permits (1) the analysis of the rate of responding over time, and (2) the analysis of the semantic relationships between words using a new method, Explicit Semantic Analysis (ESA), as well as the established semantic clustering and switching measures developed by Troyer et al. (1997). In Experiment 1, we gathered normative data from 180 subjects ranging in age from 18 to 82 years in semantic (“animals”) and phonemic (letter “F”) conditions. The number of words retrieved in 90 s correlated with education and daily hours of computer-use. The rate of word production declined sharply over time during both tests. In semantic conditions, correct-word scores correlated strongly with the number of ESA and Troyer-defined semantic switches as well as with an ESA-defined semantic organization index (SOI). In phonemic conditions, ESA revealed significant semantic influences in the sequence of words retrieved. In Experiment 2, we examined the test-retest reliability of different measures across three weekly tests in 40 young subjects. Different categories were used for each semantic (“animals”, “parts of the body”, and “foods”) and phonemic (letters “F”, “A”, and “S”) condition. After regressing out the influences of education and computer-use, we found that correct-word z-scores in the first session did not differ from those of the subjects in Experiment 1. Word production was uniformly greater in semantic than phonemic conditions. Intraclass correlation coefficients (ICCs) of correct-word z-scores were higher for phonemic (0.91) than semantic (0.77) tests. In semantic conditions, good reliability was also seen for the SOI (ICC = 0.68) and ESA-defined switches in semantic categories (ICC = 0.62). In Experiment 3, we examined the performance of subjects from Experiment 2 when instructed to malinger: 38% showed abnormal (p< 0.05) performance in semantic conditions. Simulated malingerers with abnormal scores could be distinguished with 80% sensitivity and 89% specificity from subjects with abnormal scores in Experiment 1 using lexical, temporal, and semantic measures. In Experiment 4, we tested patients with mild and severe traumatic brain injury (mTBI and sTBI). Patients with mTBI performed within the normal range, while patients with sTBI showed significant impairments in correct-word z-scores and category shifts. The lexical, temporal, and semantic measures of the C-VF provide an automated and comprehensive description of verbal fluency performance.

Initial assessment of reliability of a self-administered web-based neuropsychological test battery

IntroductionWeb-based neuropsychological testing can be an important tool in meeting the increasing demands for neuropsychological assessment in the clinic and in large research studies. The primary aim of this study was to investigate practice effects and reliability of self-administered web-based neuropsychological tests in Memoro. Due to lack of consistent analysis and reporting of reliability in the literature, especially intraclass correlation coefficients (ICC), we highlight how using different ICC measures results in different estimates of reliability. Method61 (31 females) participants (mean age 53.3 years) completed the Memoro tests twice with a median of 14 days between testing. ResultsPractice effects were detected for all cognitive measures (d = 0.32–0.61), most pronounced for memory measures. Reliability estimated using two-way random effects single measure absolute agreement ICC(2,1) were between 0.55 and 0.74. Two-way mixed effects average measure consistency ICC(3,2), ranged from 0.79 to 0.89. Reliability was highest for the processing speed task and lower for the memory tasks. ConclusionsMemoro tests had test-retest reliability similar to that of traditional, computerized and web-based test batteries used clinically and in research. It is important to carefully choose and specify the ICC implemented, as ICC(2,1) and ICC(3,2) give different results and reflect reliability of different measures.

Comparison of measures of morphosyntactic complexity in French-speaking school-aged children

This study examined the validity and reliability of different measures of morphosyntactic complexity, including the Morphosyntactic Complexity Scale (MSCS), a novel adaptation of the Developmental Sentence Scoring, in French-speaking school-aged children. Seventy-three Quebec children from kindergarten to Grade 3 completed a definition task and a narration task. Mean length of utterance (MLU), clause density and MSCS global score, average frequency scores and average complexity scores were calculated from the transcripts of the two contexts. MLU, clause density and MSCS global score were correlated with vocabulary knowledge and narrative skills, and they increased as a function of school level, suggesting that they are valid measures of morphosyntactic complexity. Moreover, the three scores were correlated across contexts, suggesting that they are also reliable measures. However, no MSCS average frequency or average complexity score was found to be both valid and reliable. These findings will guide researchers and practitioners who desire to assess the language skills of French-speaking school-aged children.

Best approach to measuring the inferior vena cava in spontaneously ventilating patients

The objective of this study was to establish the reliability of different measurements of inferior vena cava (IVC) size and respiratory variation in response to changes in circulating volume. Transabdominal ultrasound measurements of the IVC were obtained in longitudinal (B and M modes) and transverse planes (B-mode height and ellipse circumference) during inspiration and expiration, and inferior vena cava collapsibility indices (IVCci) were calculated. Measurements were repeated following venesection of ∼450 ml. Thirty patients underwent venesection. Their IVCci increased significantly for transverse and longitudinal height measurements following venesection, but not for transverse circumference measurements. Transverse views were inadequate in 27% of patients, compared with 7% for longitudinal views (P=0.04). Changes in IVCci are sensitive to small changes in circulating volume. Measurements are most frequently achieved in the longitudinal plane. There is an urgent need for standardization of sonographic IVC measurement techniques.

Measurement of the visual contribution to postural steadiness from the COP movement: methodology and reliability

We studied the reliability of different measures of the visual contribution to postural steadiness by recording the postural sway during standing with eyes open (EO) or eyes closed (EC). The COP trajectory was recorded in 21 subjects aged 42-61 standing on a firm or foam support. The improvement of postural steadiness due to vision was measured with a higher reliability (i.e. lower intra- and inter-subject variabilities) with the sway velocity V, than with the position RMS. Due to the increase of the variability of V and RMS with their own mean values, we quantified the visual contribution to posture by the stabilization ratio (SR), based on a logarithm transform of V or RMS. As compared to the Romberg quotient (EC/EO), SR improved the reliability of the measurement of the visual contribution to posture within individuals, across subjects, and even across different studies in the literature. Our method led to decrease the inter-subject coefficient of variation of this measurement to about 25%, using a foam support. It leads to a similar accuracy in binocular and monocular vision, and it also applies to the quantification of other non-visual sensory contributions to posture.

Reliability of a new measure of H-reflex excitability.

This study examined the intraclass reliability of different measures extracted from Hoffmann reflex (H-reflex) stimulus-response curve that are used to assess neuromuscular excitability. The following measures were compared: (1) the peak-to-peak amplitude of the H-reflex at a stimulus intensity associated with 5% of the maximum M-wave; (2) the slope of the regression line of the H-reflex stimulus-response curve; and (3) the peak of the first derivative of the H-reflex stimulus-response curve, a new measure introduced in this paper. The H-reflex was elicited in the soleus for 24 subjects (12 males and 12 females) on 5 separate days. Vibration was applied to the Achilles tendon prior to stimulation to test the sensitivity of the measures on test day 4. The stimulus intensity was gradually increased from below the threshold for an H-reflex response to above the maximum M-wave (Mmax) response. The means of 5 evoked potentials at each intensity level were used to create both the H-reflex and M-wave stimulus-response curves for each subject across test days. Determination of reliability involves the consideration of both the stability and consistency of the measures. A repeated measures analysis of variance evaluated the stability of the group means across test sessions. The consistency of scores within individuals was determined by calculating the intraclass correlation coefficient (ICC). Calculation of the 95% confidence interval of estimation was used to assess significant differences between ICCs. The H-reflex measures were both stable and consistent across the first 3 test days. Achilles tendon vibration resulted in a profound reduction (59-70%) on test day 4, and then there was a return to baseline levels on test day 5. The ICC for H-reflex at a stimulus intensity associated with 5% of the maximum M-wave was 0.85. The ICC for the slope of the regression line of the H-reflex stimulus-response curve was 0.79, while it was 0.89 for the peak of the first derivative of the H-reflex stimulus-response curve. However, there was no statistical significance (P>0.05) between the 3 EMG measures of the H-reflex arc. Maximum M-wave amplitude had an ICC of 0.96 attesting to careful methodological controls. The peak of the first derivative of the H-reflex stimulus-response curve was shown to have comparable sensitivity and reliability as other more established measures. The first derivative of the H-reflex stimulus-response curve provides the rate of change, rather than amplitude, making it a robust measure of reflex arc excitability. The higher ICC for the first derivative offers greater statistical power, which is of practical significance.

Assessment criteria for output gap estimates

This paper assesses the statistical reliability of different measures of the output gap for the Euro-11 area and the US using output, inflation and unemployment systems. In order to assess the reliability of an output gap estimate three criteria are adopted. Firstly, the estimate should have forecasting power over inflation. Secondly, the ex post statistical revisions of the output gap should not differ significantly from previously computed measures. Thirdly, the estimate of the output gap should be positively correlated with standard measures of capacity utilization. We find that under our multivariate specification, unobservable components (UC) type models of the output gap show temporal consistency between sequential and final estimates and are consistent with known cyclical indicators. On the other hand, our UC models for the output gap have limited forecasting power for inflation, since they underperform an arbitrary autoregressive model.

Assessment Criteria for Output Gap Estimates

This paper assesses the statistical reliability of different measures of the output gap for the Euro-11 area and the US using output, inflation and unemployment systems. In order to assess the reliability of an output gap estimate two criteria are adopted. Firstly, the estimate should have forecasting power over inflation. Secondly, the ex post statistical revisions of the output gap should not differ significantly from previously computed measures. As an additional check on reliability, we find out whether the estimate of the output gap is positively correlated with standard measures of capacity utilization. We find that under our multivariate specification, unobservable components (UC) type models of the output gap show temporal consistency between sequential and final estimates and are consistent with known cyclical indicators. On the other hand, our UC models for the output gap have limited forecasting power for inflation, since they underperform an arbitrary autoregressive model.

Predicting bankruptcy in the retail sector: an examination of the validity of key measures of performance

The large number and size of bankruptcies in the increasingly competitive retail environment necessitates a review of our ability to signal financial distress in retailing companies. The paper shows that it is still possible to predict upcoming retail failure up to six years in advance. Thus bankruptcy prediction models can be an important diagnoostic tool for managers, wishing to identify problems early and take corrective action. Our study attempts to reconcile the contradictions in the extant literature concerning the reliability of different measures used to predict bankruptcy for the retail sector. Past problems in the ability to predict financial distress in retailers using general models can be explained by capitalizing lease and rental payments made by lessees. Once the tendency of retailers to rent rather than own is accommodated, models predict successfully. Contrary to popular belief, variables that are purported to be particularly relevant to retailers such as cash flow and inventory turnover do not improve the warning signals available from conventional bankruptcy models.