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Mobility tasks like the Timed Up and Go test (TUG), cognitive TUG (cogTUG), and walking with turns provide insights into the impact of Parkinson's disease (PD) on motor control, balance, and cognitive function. We assess the test–retest reliability of these tasks in 262 PD participants and 50 controls by evaluating machine learning models based on wearable-sensor-derived measures and statistical metrics. This evaluation examines total duration, subtask duration, and other quantitative measures across two trials. We show that the diagnostic accuracy for distinguishing PD from controls decreases by a mean of 1.8% between the first and the second trial, suggesting that task repetition may not be necessary for accurate diagnosis. Although the total duration remains relatively consistent between trials (intraclass correlation coefficient (ICC) = 0.62 to 0.95), greater variability is seen in subtask duration and sensor-derived measures, reflected in machine learning performance and statistical differences. Our findings also show that this variability differs not only between controls and PD participants but also among groups with varying levels of PD severity, indicating the need to consider population characteristics. Relying solely on total task duration and conventional statistical metrics to gauge the reliability of mobility tasks may fail to reveal nuanced variations in movement. [ABSTRACT FROM AUTHOR]

The main aim of this study is to use comprehensive statistical analyses to evaluate measurement reliability of selected variables that characterize postural stability. The study examined twenty-nine healthy non-athlete students. The examinations were performed twice, with a one-week interval. The Microgate GYKO inertial sensor system was used to evaluate the reliability of variables that characterize postural stability. The relative reliability of the repeated test was evaluated using the intraclass correlation coefficient (ICC) with 95% confidence interval (95% CI). Next, the standard error of measurement (SEM) and minimal detectable change (MDC) were computed. Relative reliability of the repeated test for all analysed variables of ICC ranged from 0.31 to 0.75. For four variables, ICC values were ca. 0.7, i.e., they can be considered as good. For four other variables, ICC ranged from 0.41 to 0.54, with these values considered fair. Satisfactory reproducibility of postural stability measurements using the GYKO inertial sensor system demonstrates that it can offer an inexpensive and efficient alternative to measurements that use force balance platforms. [ABSTRACT FROM AUTHOR]

The main aim of this study is to use comprehensive statistical analyses to evaluate measurement reliability of selected variables that characterize postural stability. The study examined twenty-nine healthy nonathlete students. The examinations were performed twice, with a one-week interval. The Microgate GYKO inertial sensor system was used to evaluate the reliability of variables that characterize postural stability. The relative reliability of the repeated test was evaluated using the intraclass correlation coefficient (ICC) with 95% confidence interval (95% CI). Next, the standard error of measurement (SEM) and minimal detectable change (MDC) were computed. Relative reliability of the repeated test for all analysed variables of ICC ranged from 0.31 to 0.75. For four variables, ICC values were ca. 0.7, i.e., they can be considered as good. For four other variables, ICC ranged from 0.41 to 0.54, with these values considered fair. Satisfactory reproducibility of postural stability measurements using the GYKO inertial sensor system demonstrates that it can offer an inexpensive and efficient alternative to measurements that use force balance platforms.

Aim: To determine the test and retest reliability of the functional head impulse test (fHIT) in healthy young adults. Materials and methods: Thirty-three healthy participants (17 women, 16 men) aged 18–30 years were included in the study. Each participant underwent the fHIT twice, 1 week apart, by the same experienced clinician. Intraclass correlation coefficients (ICCs) were used to determine test–retest reliability. Results: There was no statistically significant difference between the results of total percentage of correct answer (CA%) of the fHIT obtained in session 1 and session 2 measurements in the lateral, anterior, and posterior semicircular canals (SCCs) (p > 0.05). ICC values for test–retest reliability were found to range from 0.619 to 0.665 for the three semicircular canals (SCCs). Conclusion: The test–retest reliability of the fHIT device was moderate. Attention, cognition, and fatigue may be the factors reducing reliability. In the diagnosis, follow-up, and rehabilitation processes of vestibular diseases in clinics, changes in the fHIT CA% can be used to assess vestibulo-ocular reflex (VOR) functionality. [ABSTRACT FROM AUTHOR]

The ocular counter roll (OCR) is a component of the vestibulo-ocular reflex (VOR) characterized by torsional eye movements in the opposite direction of the head during head tilt.This study aimed to determine the test-retest reliability of the video ocular counter-roll (vOCR) test, based on video-oculography (VOG) measurements, in assessing otolith function.The study included 40 healthy participants (25 females and 15 males) aged 18–44 years. Each participant underwent the vOCR test twice in 300 lateral head tilt positions 1 week apart. Test-retest reliability was assessed using intraclass correlation coefficients (ICCs), and paired t-tests and Wilcoxon signed-rank tests were used to compare the mean values of the measurements.There were no significant differences between the initial and retest measurements (p>0.05). The ICC for left head tilt was 85.2%, and for right head tilt was 79.3%, both indicating excellent reliability (p<0.01). The ICC for vOCR asymmetry was 50.7%, indicating moderate reliability (p<0.05).The vOCR test demonstrated high reliability for lateral head tilts and was found to be a reliable tool for evaluating otolith function, supporting its use in the diagnosis and treatment of vestibular disorders. [ABSTRACT FROM AUTHOR]

Introduction: We investigated the utility of the Telephone‐Montreal Cognitive Assessment (T‐MoCA) to track cognition in a diverse sample from the Einstein Aging Study. Methods: Telephone and in‐person MoCA data, collected annually, were used to evaluate longitudinal cognitive performance. Joint models of T‐MoCA and in‐person MoCA compared changes, variance, and test‐retest reliability measured by intraclass correlation coefficient by racial/ethnic group. Results: There were no significant differences in baseline performance or longitudinal changes across three study waves for both MoCA formats. T‐MoCA performance improved over waves 1–3 but declined afterward. Test‐retest reliability was lower for the T‐MoCA than for the in‐person MoCA. In comparison with non‐Hispanic Whites, non‐Hispanic Blacks and Hispanics performed worse at baseline on both MoCA formats and showed lower correlations between T‐MoCA and in‐person versions. Conclusions: The T‐MoCA provides valuable information on cognitive change, despite racial/ethnic disparities and practice effects. We discuss implications for health disparity populations. Highlights: We assessed the comparability of Telephone‐Montreal Cognitive Assessment (T‐MoCA) and in‐person MoCA for tracking cognition.Changes within 3 years in T‐MoCA were similar to that for the in‐person MoCA.T‐MoCA is subject to practice effects and shows difference in performance by race/ethnicity.Test‐retest reliability of T‐MoCA is lower than that for in‐person MoCA. [ABSTRACT FROM AUTHOR]

Test–retest reliability is essential for using resting-state functional magnetic resonance imaging (rs-fMRI) as a potential biomarker for Alzheimer's disease (AD), especially when monitoring longitudinal changes and treatment effects. In addition, test–retest variability itself might represent a feature of AD. Using 3.0 T rs-fMRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we examined the long-term (1-year) test–retest reliability of resting-state networks (RSNs) in 31 healthy elderly subjects, 63 patients with mild cognitive impairment (MCI), and 17 patients with AD by applying temporal concatenation group independent component analysis and dual regression. The intraclass correlation coefficient estimates of RSN amplitudes ranged from 0.44 to 0.77 in healthy elderly subjects, from 0.31 to 0.62 in patients with MCI, and from −0.06 to 0.44 in patients with AD. The overall test–retest reliability of RSNs was lower in patients with MCI than in healthy elderly subjects, and was lower in patients with AD than in patients with MCI. The differences in the test–retest reliabilities were due to the RSN amplitudes rather than the RSN shapes. Head motion was not significantly different among the three groups of subjects. The results indicate that the test–retest stability of RSNs generally declines with progression to MCI and AD, mainly due to the RSN amplitudes rather than the RSN shapes. The test–retest instability in MCI and AD may reflect progressive neurofunctional alterations related to the pathology of AD. • Test–retest reliability of resting-state networks (RSNs) in MCI and AD is unclear. • Test–retest RSN stability usually declines with progression to MCI and AD. • Test–retest instability is mainly due to RSN amplitudes rather than RSN shapes. • Test–retest instability may reflect neurofunctional alterations due to AD. [ABSTRACT FROM AUTHOR]

The intraclass correlation coefficient (ICC) is a classical index of measurement reliability. With the advent of new and complex types of data for which the ICC is not defined, there is a need for new ways to assess reliability. To meet this need, we propose a new distance‐based ICC (dbICC), defined in terms of arbitrary distances among observations. We introduce a bias correction to improve the coverage of bootstrap confidence intervals for the dbICC, and demonstrate its efficacy via simulation. We illustrate the proposed method by analyzing the test‐retest reliability of brain connectivity matrices derived from a set of repeated functional magnetic resonance imaging scans. The Spearman‐Brown formula, which shows how more intensive measurement increases reliability, is extended to encompass the dbICC. [ABSTRACT FROM AUTHOR]

Abstract Introduction The basic paradigm of rehabilitation is based on the brain plasticity, and for promoting it, test–retest reliability (TRR) of brain activation in which certain area of the brain is repeatedly activated is required. In this study, we investigated whether the robotic passive movement has the TRR of brain activation. While active training has been shown to have TRR, but there still have been arguments over the TRR by passive movement. Methods In order to test TRR, 10 repetitive sessions and various intervals (1 day, 3 days, 7 days, 23 days, 15 min, and 6 hr) were applied to five subjects, which had the same statistical power as applying two sessions to 50 subjects. In each session, three robot speeds (0.25, 0.5, and 0.75 Hz) were applied to provide passive movement using the robot. The fNIRS signal (oxy‐Hb) generated in the primary sensorimotor area (SM1) was measured on a total of 29 channels. At this time, we used activation maps and intraclass correlation coefficient (ICC) values to examine the TRR and the effect of robot speeds and intervals on TRR. Results As a result, activation maps showed prominent variation regardless of robot speeds and interval, and the ICC value (=0.002) showed no TRR of brain activation for robotic passive movement. Conclusion The brain activation induced by the robotic passive movement alone has very poor TRR, suggesting that further enhancement is required to strengthen the TRR by complementing active user engagements.

The YOUth cohort study is a unique longitudinal study on brain development in the general population. As part of the YOUth study, 2000 children will be included at 8, 9 or 10 years of age and planned to return every three years during adolescence. Magnetic resonance imaging (MRI) brain scans are collected, including structural T1-weighted imaging, diffusion-weighted imaging (DWI), resting-state functional MRI and task-based functional MRI. Here, we provide a comprehensive report of the MR acquisition in YOUth Child & Adolescent including the test-retest reliability of brain measures derived from each type of scan. To measure test-retest reliability, 17 adults were scanned twice with a week between sessions using the full YOUth MRI protocol. Intraclass correlation coefficients were calculated to quantify reliability. Global brain measures derived from structural T1-weighted and DWI scans were reliable. Resting-state functional connectivity was moderately reliable, as well as functional brain measures for both the inhibition task (stop versus go) and the emotion task (face versus house). Our results complement previous studies by presenting reliability results of regional brain measures collected with different MRI modalities. YOUth facilitates data sharing and aims for reliable and high-quality data. Here we show that using the state-of-the art YOUth MRI protocol brain measures can be estimated reliably.

Purpose The aim of this study was to analyse absolute and relative reliability of a number of postural static stability measures obtained from a GYKO inertial sensor system in young adults. Methods The study examined 29 healthy non-athlete young adults. A test was performed for 30 s while standing on one foot, without moving, with eyes open and arms relaxed along the sides of the body. The examinations were performed twice, with a one-week interval. Relative reliability was measured using the intraclass correlation coefficient (ICC) and the 95% confidence interval (95% CI), whereas the absolute reliability was evaluated based on the standard error of measurement (SEM) and the minimal detectable change (MDC). Results The results of this study showed moderate to good relative reliability scores for all the postural stability measures, with ICC values ranging from 0.62 to 0.70. For most of the analysed variables, SEM% ranged from ca. 10% to 14%. Relatively high SEM% values were obtained only for two variables (Area, Convex Hull Area). Conclusions The low costs of GYKO inertial sensor systems, the fast and easy installation, the mobility and high reliability of the measurement of postural stability show that it can be effective alternative to stabilographic platforms. [ABSTRACT FROM AUTHOR]

• High-density EEG was collected during treadmill walking and seated conditions. • Assessed long-term test-retest reliability of the N2 and P3 event-related potentials. • Adequate to excellent N2/P3 stability was found during sitting and walking. • Demonstration of reliability is essential for translational application of MoBI technique. Advancements in acquisition technology and signal-processing techniques have spurred numerous recent investigations on the electro-cortical signals generated during whole-body motion. This approach, termed Mobile Brain/Body Imaging (MoBI), has the potential to elucidate the neural correlates of perceptual and cognitive processes during real-life activities, such as locomotion. However, as of yet, no one has assessed the long-term stability of event-related potentials (ERPs) recorded under these conditions. Therefore, the objective of the current study was to evaluate the test-retest reliability of cognitive ERPs recorded while walking. High-density EEG was acquired from 12 young adults on two occasions, separated by an average of 2.3 years, as they performed a Go/No-Go response inhibition paradigm. During each testing session, participants performed the task while walking on a treadmill and seated. Using the intraclass correlation coefficient (ICC) as a measure of agreement, we focused on two well-established neurophysiological correlates of cognitive control, the N2 and P3 ERPs. Following ICA-based artifact rejection, the earlier N2 yielded good to excellent levels of reliability for both amplitude and latency, while measurements for the later P3 component were generally less robust but still indicative of adequate to good levels of stability. Interestingly, the N2 was more consistent between walking sessions, compared to sitting, for both hits and correct rejection trials. In contrast, the P3 waveform tended to have a higher degree of consistency during sitting conditions. Overall, these results suggest that the electro-cortical signals obtained during active walking are representative of stable indices of neurophysiological function. [ABSTRACT FROM AUTHOR]

Purpose: The US Food and Drug Administration (FDA) 2009 guidance for industry on patient-reported outcome (PRO) measures describes how the Agency evaluates the psychometric properties of measures intended to support medical product labeling claims. An important psychometric property is test-retest reliability. The guidance lists intraclass correlation coefficients (ICCs) and the assessment time period as key considerations for test-retest reliability evaluations. However, the guidance does not provide recommendations regarding ICC computation, nor is there consensus within the measurement literature regarding the most appropriate ICC formula for test-retest reliability assessment. This absence of consensus emerged as an issue within Critical Path Institute's PRO Consortium. The purpose of this project was to generate thoughtful and informed recommendations regarding the most appropriate ICC formula for assessing a PRO measure's test-retest reliability.Methods: Literature was reviewed and a preferred ICC formula was proposed. Feedback on the chosen formula was solicited from psychometricians, biostatisticians, regulators, and other scientists who have collaborated on PRO Consortium initiatives.Results and Conclusions: Feedback was carefully considered and, after further deliberation, the proposed ICC formula was confirmed. In conclusion, to assess test-retest reliability for PRO measures, the two-way mixed-effect analysis of variance model with interaction for the absolute agreement between single scores is recommended. [ABSTRACT FROM AUTHOR]

To date, only one study has examined test–retest reliability of resting state fMRI (R-fMRI) in children, none in clinical developing groups. Here, we assessed short-term test–retest reliability in a sample of 46 children (11–17.9 years) with attention-deficit/hyperactivity disorder (ADHD) and 57 typically developing children (TDC). Our primary test–retest reliability measure was the intraclass correlation coefficient (ICC), quantified for a range of R-fMRI metrics. We aimed to (1) survey reliability within and across diagnostic groups, and (2) compare voxel-wise ICC between groups. We found moderate-to-high ICC across all children and within groups, with higher-order functional networks showing greater ICC. Nearly all R-fMRI metrics exhibited significantly higher ICC in TDC than in children with ADHD for one or more regions. In particular, posterior cingulate and ventral precuneus exhibited group differences in ICC across multiple measures. In the context of overall moderate-to-high test–retest reliability in children, regional differences in ICC related to diagnostic groups likely reflect the underlying pathophysiology for ADHD. Our currently limited understanding of the factors contributing to inter- and intra-subject variability in ADHD underscores the need for large initiatives aimed at examining their impact on test–retest reliability in both clinical and developing populations.

Abstract: The hippocampal formation is a complex brain structure that is important in cognitive processes such as memory, mood, reward processing and other executive functions. Histological and neuroimaging studies have implicated the hippocampal region in neuropsychiatric disorders as well as in neurodegenerative diseases. This highly plastic limbic region is made up of several subregions that are believed to have different functional roles. Therefore, there is a growing interest in imaging the subregions of the hippocampal formation rather than modelling the hippocampus as a homogenous structure, driving the development of new automated analysis tools. Consequently, there is a pressing need to understand the stability of the measures derived from these new techniques. In this study, an automated hippocampal subregion segmentation pipeline, released as a developmental version of Freesurfer (v6.0), was applied to T1‐weighted magnetic resonance imaging (MRI) scans of 22 healthy older participants, scanned on 3 separate occasions and a separate longitudinal dataset of 40 Alzheimer's disease (AD) patients. Test–retest reliability of hippocampal subregion volumes was assessed using the intra‐class correlation coefficient (ICC), percentage volume difference and percentage volume overlap (Dice). Sensitivity of the regional estimates to longitudinal change was estimated using linear mixed effects (LME) modelling. The results show that out of the 24 hippocampal subregions, 20 had ICC scores of 0.9 or higher in both samples; these regions include the molecular layer, granule cell layer of the dentate gyrus, CA1, CA3 and the subiculum (ICC > 0.9), whilst the hippocampal fissure and fimbria had lower ICC scores (0.73–0.88). Furthermore, LME analysis of the independent AD dataset demonstrated sensitivity to group and individual differences in the rate of volume change over time in several hippocampal subregions (CA1, molecular layer, CA3, hippocampal tail, fissure and presubiculum). These results indicate that this automated segmentation method provides a robust method with which to measure hippocampal subregions, and may be useful in tracking disease progression and measuring the effects of pharmacological intervention. [ABSTRACT FROM AUTHOR]

Introduction: To facilitate large-scale assessment of a variety of cognitive abilities in clinical studies, we developed a self-administered online neuropsychological test battery: the Amsterdam Cognition Scan (ACS). The current studies evaluate in a group of adult cancer patients: test–retest reliability of the ACS and the influence of test setting (home or hospital), and the relationship between our online and a traditional test battery (concurrent validity).Method: Test–retest reliability was studied in 96 cancer patients (57 female;Mage = 51.8 years) who completed the ACS twice. Intraclass correlation coefficients (ICCs) were used to assess consistency over time. The test setting was counterbalanced between home and hospital; influence on test performance was assessed by repeated measures analyses of variance. Concurrent validity was studied in 201 cancer patients (112 female;Mage = 53.5 years) who completed both the online and an equivalent traditional neuropsychological test battery. Spearman or Pearson correlations were used to assess consistency between online and traditional tests.Results: ICCs of the online tests ranged from .29 to .76, with an ICC of .78 for the ACS total score. These correlations are generally comparable with the test–retest correlations of the traditional tests as reported in the literature. Correlating online and traditional test scores, we observed medium to large concurrent validity (r/ρ = .42 to .70; total scorer = .78), except for a visuospatial memory test (ρ = .36). Correlations were affected—as expected—by design differences between online tests and their offline counterparts.Conclusions: Although development and optimization of the ACS is an ongoing process, and reliability can be optimized for several tests, our results indicate that it is a highly usable tool to obtain (online) measures of various cognitive abilities. The ACS is expected to facilitate efficient gathering of data on cognitive functioning in the near future. [ABSTRACT FROM AUTHOR]

Background: Auditory-evoked potentials have proven useful in the objective evaluation of sound encoding at different stages of the auditory pathway (brainstem and cortex). Yet, their utility for use in clinical assessment and empirical research relies critically on the precision and test-retest repeatability of the measure. Purpose: To determine how subcortical/cortical classes of auditory neural responses directly compare in terms of their internal consistency and test-retest reliability within and between listeners. Research Design: A descriptive cohort study describing the dispersion of electrophysiological measures. Study Sample: Eight young, normal-hearing female listeners. Data Collection and Analysis: We recorded auditory brainstem responses (ABRs), brainstem frequency-following responses (FFRs), and cortical (P1-N1 -P2) auditory-evoked potentials elicited by speech sounds in the same set of listeners. We reassessed responses within each of four different test sessions over a period of 1 mo, allowing us to detect possible changes in latency/amplitude characteristics with finer detail than in previous studies. Results: Our findings show that brainstem and cortical amplitude/latency measures are remarkably stable; with the exception of slight prolongation of the P1 wave, we found no significant variation in any response measure. Intraclass correlation analysis revealed that the speech-evoked FFR amplitude and latency measures achieved superior repeatability (intraclass correlation coefficient >0.85) among the more widely used obligatory brainstem (ABR) and cortical (P1-N1-P2) auditory-evoked potentials. Contrasting these intersubject effects, intrasubject variability (i.e., within-subject coefficient of variation) revealed that while latencies were more stable than amplitudes, brainstem and cortical responses did not differ in their variability at the single subject level. Conclusions: We conclude that (1) the variability of auditory neural responses increases with ascending level along the auditory neuroaxis (cortex > brainstem) between subjects but remains highly stable within subjects and (2) speech-FFRs might provide a more stable measure of auditory function than other conventional responses (e.g., click-ABR), given their lower inter- and intrasubject variability. [ABSTRACT FROM AUTHOR]

Oscillatory activity in the beta frequency range (15–30 Hz) recorded from human sensorimotor cortex is of increasing interest as a putative biomarker of motor system function and dysfunction. Despite its increasing use in basic and clinical research, surprisingly little is known about the test-retest reliability of spectral power and peak frequency measures of beta oscillatory signals from sensorimotor cortex. Establishing that these beta measures are stable over time in healthy populations is a necessary precursor to their use in the clinic. Here, we used scalp electroencephalography (EEG) to evaluate intra-individual reliability of beta-band oscillations over six sessions, focusing on changes in beta activity during movement (Movement-Related Beta Desynchronization, MRBD) and after movement termination (Post-Movement Beta Rebound, PMBR). Subjects performed visually-cued unimanual wrist flexion and extension. We assessed Intraclass Correlation Coefficients (ICC) and between-session correlations for spectral power and peak frequency measures of movement-related and resting beta activity. Movement-related and resting beta power from both sensorimotor cortices was highly reliable across sessions. Resting beta power yielded highest reliability (average ICC=0.903), followed by MRBD (average ICC=0.886) and PMBR (average ICC=0.663). Notably, peak frequency measures yielded lower ICC values compared to the assessment of spectral power, particularly for movement-related beta activity (ICC=0.386–0.402). Our data highlight that power measures of movement-related beta oscillations are highly reliable, while corresponding peak frequency measures show greater intra-individual variability across sessions. Importantly, our finding that beta power estimates show high intra-individual reliability over time serves to validate the notion that these measures reflect meaningful individual differences that can be utilised in basic research and clinical studies. [ABSTRACT FROM AUTHOR]

Event-related potentials (ERPs) have been widely used to investigate brain functioning in children with Attention Deficit Hyperactivity Disorder (ADHD) in both research and diagnostic settings. To ensure the efficiency of ERP techniques in ADHD diagnosis and in longitudinal observational studies, the test-retest reliability of the affected population must be validated. Thus, the present article assesses the short-term test-retest reliability of certain early and late ERPs (i.e., P1, N1, N2, P2, P3), as well as independent components (ICs) decomposed from the above mentioned ERPs (IC P3 Go, IC P3 NoGo early, IC P3 NoGo late) relevant to ADHD, through the Intraclass Correlation Coefficient (ICC). More specifically, we employ a cued visual Go/NoGo paradigm for recording ERPs from 22 children with ADHD (mean age 12.2), twice within 30 min. Amplitudes and latencies are calculated by the ‘peak amplitude’ method and by a variation of the fractional area. Results for amplitudes lie mostly within the ‘good’ and ‘excellent’ range for both measurement methods, while ICC for latencies is more variable ranging from ‘poor’ to ‘excellent’ results. Crucially, the ICs, which are associated with distinct functionally independent processes of the executive attentional system have shown a comparable test-retest reliability with the raw ERPs. Our results are consistent with other reliability studies of neurotypical population in the literature, and as such, consist initial evidence that ERPs could be reliable neurophysiological markers for the ADHD population. [ABSTRACT FROM AUTHOR]

To date, only one study has examined test–retest reliability of resting state fMRI (R-fMRI) in children, none in clinical developing groups. Here, we assessed short-term test–retest reliability in a sample of 46 children (11–17.9 years) with attention-deficit/hyperactivity disorder (ADHD) and 57 typically developing children (TDC). Our primary test–retest reliability measure was the intraclass correlation coefficient (ICC), quantified for a range of R-fMRI metrics. We aimed to (1) survey reliability within and across diagnostic groups, and (2) compare voxel-wise ICC between groups. We found moderate-to-high ICC across all children and within groups, with higher-order functional networks showing greater ICC. Nearly all R-fMRI metrics exhibited significantly higher ICC in TDC than in children with ADHD for one or more regions. In particular, posterior cingulate and ventral precuneus exhibited group differences in ICC across multiple measures. In the context of overall moderate-to-high test–retest reliability in children, regional differences in ICC related to diagnostic groups likely reflect the underlying pathophysiology for ADHD. Our currently limited understanding of the factors contributing to inter- and intra-subject variability in ADHD underscores the need for large initiatives aimed at examining their impact on test–retest reliability in both clinical and developing populations. [ABSTRACT FROM AUTHOR]

Test-retest reliability of neuroimaging measurements is an important concern in the investigation of cognitive functions in the human brain. To date, intraclass correlation coefficients (ICCs), originally used in interrater reliability studies in behavioral sciences, have become commonly used metrics in reliability studies on neuroimaging and functional near-infrared spectroscopy (fNIRS). However, as there are six popular forms of ICC, the adequateness of the comprehensive understanding of ICCs will affect how one may appropriately select, use, and interpret ICCs toward a reliability study. We first offer a brief review and tutorial on the statistical rationale of ICCs, including their underlying analysis of variance models and technical definitions, in the context of assessment on intertest reliability. Second, we provide general guidelines on the selection and interpretation of ICCs. Third, we illustrate the proposed approach by using an actual research study to assess intertest reliability of fNIRS-based, volumetric diffuse optical tomography of brain activities stimulated by a risk decision- making protocol. Last, special issues that may arise in reliability assessment using ICCs are discussed and solutions are suggested. [ABSTRACT FROM AUTHOR]

PURPOSE: Reproductive factors are often evaluated in epidemiologic interview studies as risk factors for diseases in women. Similarly, childhood social class has been implicated in the etiology of several diseases. Nevertheless, questions related to these factors have not been thoroughly evaluated for test-retest reliability. This research measured the test-retest reliability of reproductive and childhood social class variables, and determined whether reliability differed by case-control status, age, educational level, time between interviews, and interviewer-rated quality of the interview.METHODS: Subjects were participants in a population-based case-control in-person interview study of Hodgkin''s disease in northern California women. Twenty-four cases and 22 controls were reinterviewed by telephone between 1992 and 1995, with an average interval of 8 months between interviews. Reliability was assessed using kappa or intraclass correlation coefficients; mean reliability coefficients and 95% confidence intervals (CIs) were estimated using the bootstrap method.RESULTS: Reliability was excellent for all variables (reliability coefficients between 0.76 and 0.96) and did not differ by case-control status (mean reliability = 0.82 for cases and 0.84 for controls), age (mean reliability = 0.85 for age < 40 and 0.82 for age &ges; 40), time between interviews (mean reliability = 0.75 for 0–5 months, 0.88 for 6–11 months, and 0.87 for 1 year or more), or interviewer-rated quality of the validity of the original responses (mean reliability = 0.93 for “not too confident” and 0.83 for “confident”). However, reliability was consistently lower among less educated women (mean reliability = 0.56 for high school or less and 0.88 for more than high school), a finding consistent with results of prior studies.CONCLUSIONS: These results indicate that questions about reproductive experience and childhood social class posed in in-person interviews can be answered reliably. However, inclusion of subjects at lower socioeconomic status may result in lower reliability for some interview responses. [Copyright &y& Elsevier]

Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall "good" relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended. [ABSTRACT FROM AUTHOR]

• Test-retest reliability of structural MRI and DWI data was good. • Test-retest reliability of resting-state and task-related fMRI was moderate. • Overall, global brain measures are more reliable than local brain measures. The YOUth cohort study is a unique longitudinal study on brain development in the general population. As part of the YOUth study, 2000 children will be included at 8, 9 or 10 years of age and planned to return every three years during adolescence. Magnetic resonance imaging (MRI) brain scans are collected, including structural T1-weighted imaging, diffusion-weighted imaging (DWI), resting-state functional MRI and task-based functional MRI. Here, we provide a comprehensive report of the MR acquisition in YOUth Child & Adolescent including the test-retest reliability of brain measures derived from each type of scan. To measure test-retest reliability, 17 adults were scanned twice with a week between sessions using the full YOUth MRI protocol. Intraclass correlation coefficients were calculated to quantify reliability. Global brain measures derived from structural T1-weighted and DWI scans were reliable. Resting-state functional connectivity was moderately reliable, as well as functional brain measures for both the inhibition task (stop versus go) and the emotion task (face versus house). Our results complement previous studies by presenting reliability results of regional brain measures collected with different MRI modalities. YOUth facilitates data sharing and aims for reliable and high-quality data. Here we show that using the state-of-the art YOUth MRI protocol brain measures can be estimated reliably. [ABSTRACT FROM AUTHOR]