Typical Error Of Measurement Research Articles

Effects of measurement error on Monte Carlo integration estimators of tree volume: sample diameters measured at random upper-stem heights

A study of the effects of measurement error was conducted on importance sampling and control variate sampling estimators of tree stem volume in which sample diameters are measured at randomly selected upper-stem heights. It was found that these estimators were unbiased in the presence of additive mean zero and multiplicative mean one measurement error applied to random samples of upper-stem diameter squared. However, biases due to measurement error are present if additive or multiplicative error is applied to upper-stem diameter rather than to upper-stem diameter squared. This is significant, as it appears that most of the previous studies on the magnitude of upper-stem diameter measurement error implicitly assume that the mean error is centered around the diameter rather than about the square of the diameter. Application of typical upper-stem measurement error obtained from previous studies to bias formulae derived here indicates that the bias could be a concern for small trees and with additive measurement error within ranges found in previous studies. Formulae for the variances of importance sampling and control variate sampling are derived, which include the contribution of both measurement error and sampling error. Results from previous studies of Monte Carlo integration estimator sampling error are combined with results from studies of upper-stem measurement error to obtain estimates of the typical magnitude of the contribution of measurement error to total estimator variability. Increases in upper-stem sample size may be warranted due to the impact of measurement error if precise estimates of stem volume at the individual-tree level are desired.

Repeatability of a running heat tolerance test

At present there is no standardised heat tolerance test (HTT) procedure adopting a running mode of exercise. Current HTTs may misdiagnose a runner's susceptibility to a hyperthermic state due to differences in exercise intensity. The current study aimed to establish the repeatability of a practical running test to evaluate individual's ability to tolerate exercise heat stress. Sixteen (8M, 8F) participants performed the running HTT (RHTT) (30min, 9kmh−1, 2% elevation) on two separate occasions in a hot environment (40°C and 40% relative humidity). There were no differences in peak rectal temperature (RHTT1: 38.82±0.47°C, RHTT2: 38.86±0.49°C, Intra-class correlation coefficient (ICC)=0.93, typical error of measure (TEM)=0.13°C), peak skin temperature (RHTT1: 38.12±0.45, RHTT2: 38.11±0.45°C, ICC=0.79, TEM=0.30°C), peak heart rate (RHTT1: 182±15 beatsmin−1, RHTT2: 183±15 beatsmin−1, ICC=0.99, TEM=2 beatsmin−1), nor sweat rate (1721±675gh−1, 1716±745gh−1, ICC=0.95, TEM=162gh−1) between RHTT1 and RHTT2 (p>0.05). Results demonstrate good agreement, strong correlations and small differences between repeated trials, and the TEM values suggest low within-participant variability. The RHTT was effective in differentiating between individuals physiological responses; supporting a heat tolerance continuum. The findings suggest the RHTT is a repeatable measure of physiological strain in the heat and may be used to assess the effectiveness of acute and chronic heat alleviating procedures.

Indirect determination of the mobility of structure-borne sound sources

Methods are considered for the indirect determination of the mobility of structure-borne sound sources. Instead of performing measurements on the source in the free state, the source mobility is obtained from measurements made in-situ. This approach is beneficial if the source is difficult to suspend, or if it contains nonlinear structural elements. Two formulations for an indirect source mobility are derived theoretically. The first requires measurement of velocities at or near to the contact points. The second involves measurement of remote velocities only. Neither of the methods requires excitation at the contacts in the coupled state. Numerical simulations of coupled beams are used to validate the two methods and investigate their accuracy and reliability with respect to typical measurement errors, such as background noise and inaccuracies in sensor positioning. It is found that these can have a significant effect on the methods considered. Several experimental case studies with single-contact and multi-contact sources are performed. The results confirm the validity of the two methods in principle, but highlight their sensitivity to experimental errors. In a representative case study with a fan unit, average errors range between ±5dB and ±10dB, with occasional errors of up to 30dB.

A novel incremental slide board test for speed skaters: Reliability analysis and comparison with a cycling test

IntroductionExercise prescription from indices obtained from cycling or running treadmill incremental tests does not seem suitable for speed skaters. However, the specificity of laboratory skating assessments remains to be established. PurposeThis study intended to assess the test–retest reliability of an incremental test performed on a slide board (SB), and its validity compared with a cycling protocol in order to determine aerobic performance indices in speed skaters. MethodsTen competitive inline speed skaters performed two incremental tests on an SB and one cycling incremental test. The intensity of SB test was determined by cadence, starting at 30 push-offs/min and increasing by three push-offs/min each minute, until volitional exhaustion. Maximal and submaximal values related to the anaerobic threshold (AT) of oxygen uptake (VO2), pulmonary ventilation (VE), respiratory exchange (RER), heart rate (HR), rating of perceived effort (RPE), cadence (CAD), and blood lactate concentration ([Lac]max) were measured. ResultsNo significant differences were found in any of the variables between test–retest on SB. High relative (ICC>0.9) and absolute reliability (typical error of measure as CVTEM<3.5%) were found for VO2max, HRmax, [Lac]max, CADmax, VO2AT, CADAT, and RPEAT. In comparison to SB test, the [Lac]max was significantly higher during cycling, and the RPEAT was lower. VO2max, HRmax, CADmax, VO2AT and CADAT were largely correlated between cycling and SB (r>0.8). ConclusionsThe findings suggest that SB test is reliable and adequate to evaluate aerobic performance indices of speed skaters.

The Trojan Lifetime Champions Health Survey: development, validity, and reliability.

Self-report questionnaires are an important method of evaluating lifespan health, exercise, and health-related quality of life (HRQL) outcomes among elite, competitive athletes. Few instruments, however, have undergone formal characterization of their psychometric properties within this population. To evaluate the validity and reliability of a novel health and exercise questionnaire, the Trojan Lifetime Champions (TLC) Health Survey. Descriptive laboratory study. A large National Collegiate Athletic Association Division I university. A total of 63 university alumni (age range, 24 to 84 years), including former varsity collegiate athletes and a control group of nonathletes. Participants completed the TLC Health Survey twice at a mean interval of 23 days with randomization to the paper or electronic version of the instrument. Content validity, feasibility of administration, test-retest reliability, parallel-form reliability between paper and electronic forms, and estimates of systematic and typical error versus differences of clinical interest were assessed across a broad range of health, exercise, and HRQL measures. Correlation coefficients, including intraclass correlation coefficients (ICCs) for continuous variables and κ agreement statistics for ordinal variables, for test-retest reliability averaged 0.86, 0.90, 0.80, and 0.74 for HRQL, lifetime health, recent health, and exercise variables, respectively. Correlation coefficients, again ICCs and κ, for parallel-form reliability (ie, equivalence) between paper and electronic versions averaged 0.90, 0.85, 0.85, and 0.81 for HRQL, lifetime health, recent health, and exercise variables, respectively. Typical measurement error was less than the a priori thresholds of clinical interest, and we found minimal evidence of systematic test-retest error. We found strong evidence of content validity, convergent construct validity with the Short-Form 12 Version 2 HRQL instrument, and feasibility of administration in an elite, competitive athletic population. These data suggest that the TLC Health Survey is a valid and reliable instrument for assessing lifetime and recent health, exercise, and HRQL, among elite competitive athletes. Generalizability of the instrument may be enhanced by additional, larger-scale studies in diverse populations.

Reliability of Musculoskeletal Fitness Tests and Movement Control Impairment Test Battery in Female Health-Care Personnel with Re-Current Low Back Pain

Background: Low back pain (LBP) is one of the most important causes of work absenteeism in health-care personnel. Low performance levels for fitness components, and movement control impairment (MCI) of the spine have been posited to be risk factors for persistent LBP. The aims of this study were to examine the long-term reliability (test I – test II) of selected motor and musculoskeletal fitness tests and the standard MCI test battery in female health-care personnel with nonspecific LBP, and to investigate associations between change in intensity of LBP and variation in test results in two measurement points. Methods: The participants (n=47) were workers in geriatric wards. Long-term reliability of six field tests assessing motor abilities, flexibility and muscular strength, and the MCI test battery were studied. Mean test I – test II time-span was 18 days (SD 7.9). The estimates of reliability for interval-scale measurements (fitness) were typical error (s) of measurement and the coefficient of variation (CV). The reliability of nominal-scale measurements was analysed by the kappa coefficient. Results: The lowest within-subject variation was found in running figure of eight test (s=0.22 s, CV=2.8%) and the highest for modified push-ups (s=1.04 repetitions, CV=12.2%). The kappa values for the dorsal pelvic tilt, sitting knee extension, the anterior pelvic tilt, and lying-prone knee flexion varied between 0.71 and 0.45 but were lower for rocking forwards and backwards (k=0.31) and the one-leg stance (k=0.16). Change in the pain intensity was associated only with variation in test I – test II results for modified push-ups (p=0.045). Conclusions: All of the tests assessing musculoskeletal fitness and four of the MCI tests had an acceptable level of long-term reliability. The two tests for MCI that had poor reliability need to be better standardised in order to serve as reliable clinical measurement tools.

The implementation of binned Kernel density estimation to determine open clusters’ proper motions: validation of the method

Stellar membership determination of an open cluster is an important process to do before further analysis. Basically, there are two classes of membership determination method: parametric and non-parametric. In this study, an alternative of non-parametric method based on Binned Kernel Density Estimation that accounts measurements errors (simply called BKDE-e) is proposed. This method is applied upon proper motions data to determine cluster's membership kinematically and estimate the average proper motions of the cluster. Monte Carlo simulations show that the average proper motions determination using this proposed method is statistically more accurate than ordinary Kernel Density Estimator (KDE). By including measurement errors in the calculation, the mode location from the resulting density estimate is less sensitive to non-physical or stochastic fluctuation as compared to ordinary KDE that excludes measurement errors. For the typical mean measurement error of 7 mas/yr, BKDE-e suppresses the potential of miscalculation by a factor of two compared to KDE. With median accuracy of about 93%, BKDE-e method has comparable accuracy with respect to parametric method (modified Sanders algorithm). Application to real data from The Fourth USNO CCD Astrograph Catalog (UCAC4), especially to NGC 2682 is also performed. The mode of member stars distribution on Vector Point Diagram is located at $\mu_{\alpha}\cos\delta=-9.94\pm0.85$ mas/yr and $\mu_{\delta}=-4.92\pm0.88$ mas/yr. Although the BKDE-e performance does not overtake parametric approach, it serves a new view of doing membership analysis, expandable to astrometric and photometric data or even in binary cluster search.

Vastus lateralis muscle cross-sectional area ultrasonography validity for image fitting in humans.

The present study aimed to determine the concurrent validity of ultrasound (US) measurement of the vastus lateralis muscle (VL) cross-sectional area (CSA) having magnetic resonance imaging (MRI) as the gold standard measurement, in a heterogeneous sample of participants. Thirty-one individuals (52.44 ± 16.37 years; 1.67 ± 0.11 m; 75.25 ± 13.82 kg) volunteered to participate in the study. All the images were performed in the right leg. Image-fitting technique (US) and computerized planimetry technique (US and MRI) were used to determine the VL CSA. The typical error (TE) of measurement was used to determine the concurrent validity of the US measurements. Our results demonstrated good validity of the US compared with the MRI measurements (TE = 0.37 cm; coefficient of variation = 1.75%). The Bland-Altman plot demonstrated bias of 0.07 ± 0.53 cm and limits of agreement of 0.96-1.11 cm. Based on our TE, bias and limits of agreement, we concluded that the US image-fitting technique is valid to assess the VL CSA in a heterogeneous sample of participants. Thereby, US can be used instead of MRI to assess changes in skeletal muscle morphology.

Are the Yo-Yo intermittent recovery test levels 1 and 2 both useful? Reliability, responsiveness and interchangeability in young soccer players

The aim of this study was to compare the reliability, internal responsiveness and interchangeability of the Yo-Yo intermittent recovery test level 1 (YY1), level 2 (YY2) and submaximal YY1 (YY1-sub). Twenty-four young soccer players (age 17 ± 1 years; height 177 ± 7 cm; body mass 68 ± 6 kg) completed each test five times within pre- and in-season; distances covered and heart rates (HRs) were measured. Reliability was expressed as typical error of measurement (TEM) and intraclass correlation coefficient (ICC). Internal responsiveness was determined as effect size (ES) and signal-to-noise ratio (ESTEM). Interchangeability was determined with correlation between training-induced changes. The TEM and ICC for distances in the YY1 and YY2 and for HR in YY1-sub were 7.3% and 0.78, 7.1% and 0.93 and 2.2% and 0.78, respectively. The ESs and ESTEMs were 0.9 and 1.9 for YY1, 0.4 and 1.2 for YY2 and −0.3 and −0.3 for YY1-sub. Correlations between YY1 vs. YY2 and YY1-sub were 0.56 to 0.84 and −0.36 to −0.81, respectively. Correlations between change scores in YY1 vs. YY2 were 0.29 and −0.21 vs. YY1-sub. Peak HR was higher in YY1 vs. YY2. The YY1 and YY2 showed similar reliability; however, they were not interchangeable. The YY1 was more responsive to training compared to YY2 and YY1-sub.

Fast Laser Spectroscopy: Dynamical Absorption Line

This paper presents analysis of the problems and principles of design of the remote, fast, and precise spectroscopic sensor, operating from the robotic platform. The typical errors of gas concentration measurement have been analyzed. It has been shown that in case of fast tunable laser spectroscopy (a sample registration time – 100ns or less) the line shape is, in principle, unrepeatable, asymmetric, and chaotically modulated at each new scan. The final composite line profile is sharper at the top as compared with a Lorentzian one and wider near the bottom. Three reasons for such specific line shape formation were considered: 1) The gas absorption line shape has been simulated by the summation of Lorentzian lines of different linewidth. The Maxwellian distribution of the molecular speeds has been used to find the molecular collisional energy distribution and related linewidths with taking into account probable number of molecules with specific impact energy; 2) Appearance of the spectral satellites when the absorption process is suddenly interrupted; 3) Spectral presentation of the collision correlation function that is modulated by massive collisions at free-flight termination. To calculate the gas concentration properly the data received from the independent sensors of pressure, temperature and humidity have been used.

Reliability of power meter calibration by mathematical modelling of treadmill cycling

New power meters that are installed on various parts of the bike entered the market recently. Calibration of power meters is essential to ensure correct power output readings for testing and training. The use of a dynamic calibration rig was proposed as the preferred method to calibrate cycle ergometers (Woods et al., 1994: International Journal of Sports Medicine, 15(4), 168-171). While this works for power meters that measure power output after its transmission through the crank axle, it is not suitable for systems installed on the pedals or the crank arm (e.g. Garmin Vector, KA©o Power, Stages, Rotor Power). Therefore, we want to propose a new method to dynamically calibrate all available power meters. The purpose of our study was to quantify the typical error of this method used to assess load characteristics of power meters. Thirty power meters (14 SRM, 8 Powertap, 5 Quarq, 3 Garmin Vector) mainly used by cyclists of the Swiss national mountain bike team were analysed. Each cyclist rode his own bike equipped with his power meter on a motorized treadmill (Poma, DA¼rrrA¶hrsdorf-Dittersbach, Germany), after executing all calibration procedures according to the manufacturer. Cyclists rode with a velocity v = 3.5 m s-1 at an inclination of I±1 = 1° and I±2 = 7°. These corresponded to power demands of approximately 1 W kg-1 and 5 W kg-1, respectively. Power output measurements were averaged over 1 min for both inclinations. The total mass m of the cyclist, his equipment and bike was measured on a calibrated scale (Model 861, Seca, Reinach, Switzerland). To eliminate any contribution of rolling or aerodynamic resistance, the difference in power output between the two inclinations was calculated as I”P = m ∙ g ∙ v ∙ (sinI±2 – sinI±1). The ratio between the measured difference and that calculated by the mathematical model was defined as the load characteristic of the power meter. A value of 1 indicates perfect agreement between the measurement and the model. The procedure was performed twice. The typical error of measurement and its 95% confidence interval for the load characteristic was calculated from the 30 repeated trials (Hopkins, 2000: Sports Medicine, 30(1), 1-15). The typical error for the load characteristic was 1.5% with a 95% confidence interval of 1.1% to 1.9%. The change in the mean from trial 1 to trial 2 was 0.1% with a 95% confidence interval of -0.7% to 0.9%. The typical error of 1.5% demonstrates a high reliability of the method used to assess the load characteristic of a power meter, which can easily be enhanced by performing multiple trials. The value for a convenient triple measurement follows as 1.5% / 31/2 = 0.9% (Hopkins, 2000). The typical error presented here is comparable to the reliability reported for the calibration with a dynamic calibration rig (Woods et al., 1994). Our calibration method is easy to administer, time efficient and independent of the power meter system, rolling resistance or cyclist riding style. Even though the method does not assess absolute power output readings, it detects systematic measurement error. To further evaluate the load characteristic, an assumption concerning the drivetrain loss is necessary. After personal communication with J. Smith (www.friction-facts.com, December 6, 2013), we assume a drivetrain loss of 2% in power output difference scores. A valid system located on the crank would therefore measure a 2% higher difference in power output than predicted by the mathematical model. We conclude, that calibrating power meters by mathematical modelling of treadmill cycling is highly reliable and convenient.

Test-retest reliability of the 30-sec Wingate Cycle Test in a trained male cohort

BACKGROUND: Test-retest reliability of performing 1–2 bouts of a 30 s Wingate (30WanT) has been shown to improve by averaging 2 bouts. OBJECTIVE: To investigate whether adding a 3 rd bout enhanced or decreased reliability. METHODS: On three occasions, 13 triathletes performed three 30WanT’s on a cycle ergometer. Peak power (PP), mean power (MP) and fatigue index (FI) reliability across bouts (Intra-session) and days (Inter-session) were tested. Mean and % change between bouts, typical errors of measurement (TEM) and intra-class correlation co-efficient (ICC) were compared between consecutive pairs of bouts and 3 bouts. Single (1 & 2), averaged 2 ( 1+2) and 3 bout ( 1+2+3) between days using TEMs and ICCs were also compared. RESULTS: Intra-session ICCs for 2 and 3 bouts for PP, MP and FI showed strong reliability (> 0.7). Three bouts had lower TEM for MP, but 2 bouts had less TEM for PP and FI. Inter-session reliability ICCs were > 0.90 for PP, 0.94 for MP and 0.82 for FI for the 1, 2 and 3 bouts with no clear difference between. CONCLUSIONS: Performing 1, 2 and 3 bouts showed high to very high reliability, with a 3rd bout not clearly reducing TEM, and in some cases introducung more variability.

Relative and absolute reliability of functional performance measures for adults with dementia living in residential aged care.

This pilot investigation aimed to assess the relative and absolute test-retest reliability of commonly used functional performance measures in older adults with dementia residing in residential aged care facilities. A total of 12 participants were tested on the Short Physical Performance Battery (SPPB), the Balance Outcome Measure for Elder Rehab (BOOMER), hand grip strength, anthropometric measures and Bio-electric Impedance Analysis (BIA). This study utilized a seven-day test-retest evaluation. Intra-class Correlation Coefficients (ICC) were used to assess relative reliability, Typical Error of Measurement (TEM) was used to assess the absolute reliability, and Bland-Altman plots were used to assess group and individual levels of agreement. With the exception of Standing Balance (ICC = 0.49), 2.4-m walk (ICC = 0.68), functional reach (ICC = 0.38), and static timed standing (ICC = 0.47), all measures demonstrated acceptable (>0.71) ICCs. However, only the anthropometric measures demonstrated acceptable levels of absolute reliability (>10% TEM). Bland-Altman analysis showed non-significant (p > 0.05) mean differences, and eight out of the 17 measures showing wide Limits of Agreement (LoA). Current measures of functional performance are demonstrably inappropriate for use with a population of older adults with dementia. Authors suggest aligning current measurement strategies with Item Response Theory as a way forward.

Why Crude Oil Vapor Pressure Should Be Tested Prior to Rail Transport

Recent crude oil rail car accidents have forced US and Canadian authorities to issue Emergency Testing Orders to ensure safe transportation of crude oils. One crucial parameter in meeting these safety requirements is the testing of the vapor pressure (VP) of crude oil. This paper explains the impact of highly volatile components inside the crude oil on the vapor pressure measurement. It describes typical VP measurement errors and discusses guidelines and technology for proper crude oil classification. It offers measurement data to show the effect of sample outgassing and to describe the impact of temperature changes and the vapor-liquid ratio (V/L) on vapor pressure test results. The second part of the paper discusses methods to measure the True Vapor Pressure (TVP) and Bubble Point Pressure (BPP) of Crude Oils for safety purposes. Key words : Crude oil; Volatility testing; Safety data sheet; Hazardous material regulations (HMR); Emergency testing order; Vapor pressure (VP); ASTM D6377; Reid vapor pressure (RVP); ASTM D323; True vapor pressure (TVP); Vapor-liquid ratio (V/L); Bubble point pressure (BPP); Floating piston cylinder (FPC)

Determinants of performance in a new test of planned agility for young elite basketball players.

To investigate the reliability and determinants of performance in a new test of planned agility in elite junior basketball players. Seventeen female (15.1±0.4 y, 176.9±11.2 cm, 65.7±10.9 kg) and 42 male (14.9±0.4 y, 193.7±8.1 cm, 79.0±12.0 kg) elite junior basketball players performed 5 fitness tests presented in a random order, including a 20-m sprint, a planned-agility test, a triple bilateral horizontal countermovement jump, and 2 triple unilateral horizontal countermovement jumps (with each leg separately). The novelty of the planned-agility test is that it included both offensive and defensive movements. The determinants of planned agility were assessed by a stepwise-regression analysis, and the reliability of the new test was evaluated by the intraclass correlation coefficient and the typical error of measurement. The main results show good reliability of the new test of planned agility. In addition, the determinants of planned-agility performance were different between genders, with sprint performance explaining 74.8% of the variance for girls, while unilateral jump performance and body mass were the most important for boys, accounting for 24.0% and 8.9% of the variance, respectively, in planned agility. These results highlight a gender effect on the determinants of planned-agility performance in young elite basketball players and suggest that straight-line sprint and unilateral horizontal tests must be implemented to test elite junior players.

Validity and Interunit Reliability of 10 Hz and 15 Hz GPS Units for Assessing Athlete Movement Demands

The purpose of this study was to assess the validity and interunit reliability of 10 Hz (Catapult) and 15 Hz (GPSports) Global Positioning System (GPS) units and investigate the differences between these units as measures of team sport athlete movement demands. A team sport simulation circuit was completed by 8 trained male participants. The movement demands examined included: total distance covered (TD), average peak speed, and the distance covered, time spent, and the number of efforts performed low-speed running (0.00-13.99 km · h(-1)), high-speed running (14.00-19.99 km · h(-1)), and very high-speed running (>20.00 km · h(-1)). The degree of difference between the 10 Hz and the 15 Hz GPS units and validity was assessed using a paired samples t-test. Pearson's correlations were also used for validity assessment. Interunit reliability was established using percentage typical error of measurement (%TEM) and intraclass correlations. The findings revealed that 10 Hz GPS units were a valid (p > 0.05) and reliable (%TEM = 1.3%) measure of TD. In contrast, the 15 Hz GPS units exhibited lower validity for TD and average peak speed. Further, as the speed of movement increased the level of error for the 10 Hz and 15 Hz GPS units increased (%TEM = 0.8-19.9). The findings from this study suggest that comparisons should not be undertaken between 10 Hz and 15 Hz GPS units. In general, the 10 Hz GPS units measured movement demands with greater validity and interunit reliability than the 15 Hz units, however, both 10 Hz and 15 Hz units provided the improved measures of movement demands in comparison to 1 Hz and 5 Hz GPS units.

Reliability of measurements of rat lateral gastrocnemius architectural parameters obtained from ultrasound biomicroscopic images.

This study used ultrasound biomicroscopy (UBM) to quantify the pennation angle (PA) and muscle thickness (MT) of rat skeletal muscle and evaluated the reliability and reproducibility of the method by statistical analysis, determining the coefficient of variation (CV), intraclass correlation coefficient (ICC) and typical error of measurement. A UBM system with a center frequency of 40 MHz was used to acquire images of the right lateral gastrocnemius of ten male Wistar rats on two different days and with two ankle positions (90° or 150°). Two independent measurements of the PA and MT were randomly performed in each of three picture frames. The analysis resulted in CVs of 10.47% and 4.81% for the PA and the MT, respectively, for the ankle at 90° and 9.24% and 5.98% for the ankle at 150°. Additionally, the ICC values ranged from 0.75 to 0.92 for the PA and 0.57 to 0.99 for the MT. Statistically significant differences between the ankle positions were observed for the PA (p = 0.00013). The reliability of the PA and MT measurements for the rat right lateral gastrocnemius, determined from the ultrasound biomicroscopy images, was high (>0.90) for the methodology proposed. This finding indicates the potential of ultrasound biomicroscopy for quantitative muscle characterization and the longitudinal examination of tissue adaptation to different conditions of use, disease and rehabilitation.

A sub-nanometre spindle error motion separation technique

Abstract This work designs and validates a spindle error motion separation technique having a sub-nanometre measurement uncertainty. This technique overcomes typical measurement error sources arising from sensor, indexing or the repositioning of the artifact. We compare and assess various known reversal and multiprobe techniques by means of a novel error analysis method. From this, we develop an improved implementation of the multiprobe technique, which by-passes accurate indexing of the artifact and sensor(s) during testing, as well as unequal sensor sensitivities, in case multiple sensors are used. This is achieved by measuring the error motion consecutively under three different orientations by rotating the stator of the spindle utilising a high-precision indexing table. These modifications result in a measurement uncertainty that is four times smaller than the conventional multiprobe technique. Furthermore, the suppression of the low-order harmonics is reduced by an optimisation of measurement angles. Finally, several experimental tests are performed to quantify the measurement uncertainty and the influence of the measurement angles on the error separation. Repeatability tests on the radial error motion of an aerostatic rotary table show a measurement uncertainty of 0.455 nm.

Retest Repeatability of Motor and Musculoskeletal Fitness Tests for Public Health Monitoring of Adult Populations

Background and purpose: Physical fitness reflects the effects of regular physical activity and is an important prognostic factor of health. Field tests of fitness can be used for public health monitoring, but their accuracy for this purpose needs to be determined. The purpose was to evaluate the adequacy of retest repeatability of nine tests of motor and musculoskeletal fitness against preset criteria. Methods: One week test-retest measurements with a single tester design were conducted. The participants we volunteers, 25 women and 26 men between ages 22 and 64. The main repeatability estimates of within subject variation were the typical error of measurement and coefficient of variation (CV). For ordinal scale measurements weighted Kappa coefficients were calculated. The CV values 10% or lower and kappa coefficient >0.60 were rated as adequately reliable for public health monitoring. In addition, the systematic chance and percent change in the mean were calculated. Results: Six tests out of nine showed adequate repeatability (CV ≤ 10% or Kappa coefficient >0.60): agility in of eight run, handgrip strength, lower extremity power in vertical jump, upper body muscular strength and trunk stabilization in modified push-up, muscular endurance in static back extension, and shoulder-neck mobility. Retest learning effect was detected for backwards tandem walk and modified push-up tests. Reliability of two tests was not studied due to a ceiling effect in results towards maximum values. High level of physical activity and fitness of the participants reduced the intra-and inter-individual variation of the test results compared to general population. Conclusions: Present study provided further knowledge on reliable fitness tests suitable for population monitoring of musculoskeletal functioning and health. These tests may also be used as outcome measures to follow the effects of exercise interventions target to participants with musculoskeletal problems.

Development of the Basketball Exercise Simulation Test: A match-specific basketball fitness test

Scanlan, A.T., Dascombe, B.J. & Reaburn, P.R.J. (2014). Development of the Basketball Exercise Simulation Test: A match-specific basketball fitness test. J. Hum. Sport Exerc., 9(3), pp.700-712. The aim of this study was to develop a reliable and valid field test that simulates the match-specific activity demands of male basketball competition. Fourteen male basketball players (mean ± SD, age: 24.9 ± 2.3 yr; stature: 187.8 ± 7.7 cm; body mass: 88.8 ± 10.5 kg) from state- (n = 6) and regional-level (n = 8) Australian competitions volunteered to participate. The Basketball Exercise Simulation Test (BEST) was developed using notational data describing the current activity demands of male basketball competition. Participants completed a repeat-sprint protocol, Yo-Yo Intermittent Recovery Test (Yo-Yo IRT) and 12-min BEST trial. Nine participants completed a further BEST trial at least 7 days later. Measures taken across the BEST included mean sprint and circuit time (s), sprint and circuit decrement (%) and total distance covered (m). Test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC), typical error of measurement, coefficient of variation (CV) and 95% confidence intervals (CI) across the two BEST trials. Criterion validity was calculated using Pearson Correlation analysis between each BEST measure and performance in the repeat-sprint protocol and Yo-Yo IRT. Mean sprint and circuit time and sprint and circuit decrement possessed high ICCs (0.92-0.99), while all measures except sprint (14.6%) and circuit decrement (16.8%) exhibited low CVs (<5%). Significant (p < 0.01) relationships were reported between mean sprint time, sprint decrement, mean circuit time and circuit decrement during the BEST and repeatsprint performance (r = 0.80-0.92), as well as Yo-Yo IRT distance (r = -0.71-0.85). The present results suggest that the BEST is a reliable and valid match-specific test for the combined assessment of basketball-related anaerobic and aerobic fitness. Key words: TEAM SPORT, FIELD-TEST, ASSESSMENT, RELIABILITY, VALIDITY.