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Concept: Measuring instrument

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BACKGROUND: The Hamilton Depression Rating Scale (HAM-D) is commonly used as a screening instrument, as a continuous measure of change in depressive symptoms over time, and as a means to compare the relative efficacy of treatments. Among several abridged versions, the 6-item HAM-D6 is used most widely in large degree because of its good psychometric properties. The current study compares both self-report and clinician-rated versions of the Hebrew version of this scale. METHODS: A total of 153 Israelis 75 years of age on average participated in this study. The HAM-D6 was examined using confirmatory factor analytic (CFA) models separately for both patient and clinician responses. RESULTS: Reponses to the HAM-D6 suggest that this instrument measures a unidimensional construct with each of the scales' six items contributing significantly to the measurement. Comparisons between self-report and clinician versions indicate that responses do not significantly differ for 4 of the 6 items. Moreover, 100% sensitivity (and 91% specificity) was found between patient HAM-D6 responses and clinician diagnoses of depression. CONCLUSION: These results indicate that the Hebrew HAM-D6 can be used to measure and screen for depressive symptoms among elderly patients.

Concepts: Likert scale, Montgomery-Åsberg Depression Rating Scale, Measuring instrument, Measurement, Major depressive disorder, Type I and type II errors, Hospital, Psychometrics

145

Impulsivity as a tendency to act quickly without considering future consequences has been proposed as a dimensional factor in bipolar disorder. It can be measured using behavioral tasks and self-report questionnaires. Previous findings revealed patients to show worse performance on at least one behavioral measure of impulsivity. Additionally, self-reported impulsivity seems to be higher among bipolar patients, both parameters being possibly associated with a more severe course of illness. In this study, our primary aim was to investigate the relationship between these two constructs of impulsivity among bipolar patients.

Concepts: Measuring instrument, Dimensional analysis, Measurement, Human behavior, Test method, Impulsivity, Psychometrics, Bipolar disorder

142

The objective of this study was to determine whether kinematic data collected by the Microsoft Kinect 2 (MK2) could be used to quantify postural stability in healthy subjects. Twelve subjects were recruited for the project, and were instructed to perform a sequence of simple postural stability tasks. The movement sequence was performed as subjects were seated on top of a force platform, and the MK2 was positioned in front of them. This sequence of tasks was performed by each subject under three different postural conditions: “both feet on the ground” (1), “One foot off the ground” (2), and “both feet off the ground” (3). We compared force platform and MK2 data to quantify the degree to which the MK2 was returning reliable data across subjects. We then applied a novel machine-learning paradigm to the MK2 data in order to determine the extent to which data from the MK2 could be used to reliably classify different postural conditions. Our initial comparison of force plate and MK2 data showed a strong agreement between the two devices, with strong Pearson correlations between the trunk centroids “Spine_Mid” (0.85 ± 0.06), “Neck” (0.86 ± 0.07) and “Head” (0.87 ± 0.07), and the center of pressure centroid inferred by the force platform. Mean accuracy for the machine learning classifier from MK2 was 97.0%, with a specific classification accuracy breakdown of 90.9%, 100%, and 100% for conditions 1 through 3, respectively. Mean accuracy for the machine learning classifier derived from the force platform data was lower at 84.4%. We conclude that data from the MK2 has sufficient information content to allow us to classify sequences of tasks being performed under different levels of postural stability. Future studies will focus on validating this protocol on large populations of individuals with actual balance impairments in order to create a toolkit that is clinically validated and available to the medical community.

Concepts: Validation, Noun class, Force platform, Measuring instrument, Center of mass, Pearson product-moment correlation coefficient, Artificial intelligence, Biomechanics

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To study the relationships between 1-2 year changes in well-known physician-rated measurements (Expanded Disability Status Scale (EDSS), Timed 25-Foot Walk (T25FW), 9-Hole Peg Test (9HPT)) and the long-term (≥ 5 years) outcome in patient-reported outcome (PRO) measures (Multiple Sclerosis Impact Scale (MSIS-29), Multiple Sclerosis Walking Scale (MSWS-12)) that reflect the patient-perceived impact of disease, in progressive MS.

Concepts: Measuring instrument, Time, Test method, Expanded Disability Status Scale, Psychometrics, Multiple sclerosis, Walking

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A simplified method for measuring the fluidic resistance (R(fluidic)) of microfluidic channels is presented, in which the electrical resistance (R(elec)) of a channel filled with a conductivity standard solution can be measured and directly correlated to R(fluidic) using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine R(fluidic) to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ∼40 to 600kPasmm(-3)) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic R(fluidic) measurements were possible in more complex microfluidic designs. Microchannel R(elec) was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems.

Concepts: Measuring instrument, Electrical resistance, Microfluidics, Ohmmeter, Electrical measurements, Test method, Metrology, Measurement

28

BACKGROUND: The Alzheimer’s Disease Assessment Scale-Cognitive Behavior section (ADAS-Cog) is the most widely used measure of cognitive performance in AD clinical trials. This key role has rightly brought its performance under increased scrutiny with recent research using traditional psychometric methods, questioning the ADAS-Cog’s ability to adequately measure early-stage disease. However, given the limitations of traditional psychometric approaches, herein we use the more sophisticated Rasch Measurement Theory (RMT) methods to fully examine the strengths and weaknesses of the ADAS-Cog, and identify potential paths toward its improvement. METHODS: We analyzed AD Neuroimaging Initiative (ADNI) ADAS-Cog data (675 measurements across four time-points over 2 years) from the AD participants. RMT analysis was undertaken to examine three broad areas: adequacy of scale-to-sample targeting; degree to which, taken together, the ADAS-Cog items adequately perform as a measuring instrument; and how well the scale measured the subjects in the current sample. RESULTS: The 11 ADAS-Cog components mapped-out a measurement continuum, worked together adequately, and were stable across different time-points and samples. However, the scale did not prove to be a good match to the patient sample supporting previous research. RMT analysis also identified problematic “gaps” and “bunching” of the components across the continuum. CONCLUSION: Although the ADAS-Cog has the building blocks of a good measurement instrument, this sophisticated analysis confirms limitations with potentially serious implications for clinical trials. Importantly, and unlike traditional psychometric methods, our RMT analysis has provided important clues aimed at solving the measurement problems of the ADAS-Cog.

Concepts: Metrology, Measuring instrument, Test method, Psychometrics, Measurement

28

For the first time compressed sampling (CS) has been applied to heart rate (HR) measurements. The signals can be reconstructed from samples far below the Nyquist rate with negligible small errors, a sampling reduction of 8 has been demonstrated in the paper. As a result, the bitrate of the CS sampler is half when compared to a normal sampler. A lower bitrate leads to a reduction in power consumption for HR measurement devices.

Concepts: Nyquist frequency, Measuring instrument, Nyquist rate, English-language films, Quantity, Aliasing, Measurement, Nyquist–Shannon sampling theorem

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The purpose of this paper is to describe the theoretical development and initial validation of the newly developed Work-Life Balance Culture Scale (WLBCS), an instrument for measuring an organizational culture that promotes the work-life balance of employees.

Concepts: Human Development Index, Organizational studies, Measuring instrument

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We aimed to review tools used to assess balance in clinical practice in children and adults with cerebral palsy (CP), to describe their content and measurement properties and to evaluate the quality of the studies that have examined these properties. CINAHL, Embase, and PubMed/MEDLINE were searched. The COnsensus-based Standards for selection of health Measurement INstruments (COSMIN) was used to assess the ‘quality of studies’ and the Terwee criteria were used to assess the ‘result of studies’. Twenty-two clinical balance tools were identified from 35 papers. The content and focus of the tools varied significantly. There was moderate or limited levels of evidence for most of the measurement properties of the tools; the strongest level of evidence was found for the Trunk Control Measurement Scale and the Level of Sitting Scale, in the category ‘maintain balance’, the Timed Up and Go and the Segmental Assessment of Trunk Control in the categories ‘achieve balance’ and ‘restore balance’ respectively. Information on responsiveness was scarce. Further studies providing better evidence for reliability and responsiveness for clinical balance tools are needed. In the meantime, results of studies evaluating effects of treatment of balance in individuals with CP should be interpreted with caution.

Concepts: Category, Assessment, Meantime, Evidence-based medicine, Measuring instrument, Cerebral palsy, Psychometrics, Evaluation

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Objective: To examine the relationship between Five times sit-to-stand Test (FTSST) and functional tests and investigate the effects of task-specific training on functional ability in children with mild to moderate cerebral palsy (CP). Methods: Twenty-one subjects were randomly assigned to experimental and control groups. Motor Assessment Scale (MAS: sit-to-stand), Pediatric Balance Scale (PBS), Functional Reach Test and FTSST were tested before training, after training and at follow-up at 6 weeks post training. Results: FTSST correlated significantly with MAS (ρ = -0.733) and with PBS (ρ = -0.813) in all children with CP. There were no significant differences in all outcomes between groups. However, FTSST and MAS in children with Gross Motor Function Classification System-Expanded and Revised levels I-II were significantly different between pre and post training within the experimental group (p = 0.03). Conclusions: FTSST is a reliable and valid functional outcome measure after the task-specific training in children with mild to moderate CP.

Concepts: Experiment, Measuring instrument, Test method, Cerebral palsy