Systematic Disagreement Research Articles

Assessment of an Oblique ECE Diagnostic for ITER

A systematic disagreement between the electron temperature measured by electron cyclotron emission (ECE) (TECE) and laser Thomson scattering (TTS), which increases with TECE, is observed in JET and TFTR plasmas, such that TECE ~ 1.2 TTS when TECE ~ 10 keV. The disagreement is consistent with a non-Maxwellian distortion in the bulk electron momentum distribution. ITER is projected to operate with Te(0) ~ 20 to 40 keV so the disagreement between TECE and TTS could be >50%, with significant physics implications. The GENRAY ray-tracing code predicts that a two-view ECE system, with perpendicular and moderately oblique viewing antennas, would be sufficient to reconstruct a two-temperature bulk distribution. If the electron momentum distribution remains Maxwellian, the moderately oblique view could still be used to measure the electron temperature profile Te(R). A viewing dump will not be required for the oblique view, and plasma refraction will be minimal. The oblique view has a similar radial resolution to the perpendicular view, but with some reduction in radial coverage. Oblique viewing angles of up to 20 deg can be implemented without a major revision to the front end of the existing ITER ECE diagnostic design.

Systematic and Random Disagreement and the Reliability of Nominal Data

Reliability is an important bottleneck for content analysis and similar methods for generating analyzable data. This is because the analysis of complex qualitative phenomena such as texts, social interactions, and media images easily escape physical measurement and call for human coders to describe what they read or observe. Owing to coders inescapable individual differences in background, the data they generate for subsequent analysis are prone to errors not typically found in mechanical measuring devices. However, most agreement measures designed to indicate whether data are sufficiently reliable to warrant subsequent analysis do not differentiate among kinds of disagreement that make data unreliable. This paper distinguishes two kinds of disagreement, systematic disagreement and random disagreement, and suggests measures of them in conjunction with the agreement coefficient α (alpha) (Krippendorff, 2004a, pp. 211–256). These measures, previously proposed for interval data (Krippendorff, 1970), are here developed for nominal data. Their importance lies in their ability to not only aid the development of reliable coding instructions but also warn researchers about two kinds of errors they face when using imperfect data.

Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplasy

Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cyt b, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu ( Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira–Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works.

Parameter estimation of inspiralling compact binaries in ground-based detectors: comparison between Monte Carlo simulations and the Fisher information matrix

The Fisher information matrix is employed in the gravitational-wave literature to quantify the statistical errors in estimating the parameters of gravitational-wave sources detectable by ground-based detectors. In particular, it is used to compute the lower bound on the variances of the parameters of the signals emitted by inspiralling compact binaries. However, the Fisher-matrix formalism is known to be valid in the strong-signal approximation only. Hence it is important to quantify the signal-to-noise ratio above which the Fisher information matrix is a reliable estimator, which can be done by performing numerical simulations. In this paper, we perform Monte Carlo simulations for the case of different source configurations of inspiralling compact binaries using 3.5 PN restricted post-Newtonian waveforms. We consider the initial LIGO design sensitivity curve. We found that for a (1.4, 10)M⊙ system, the Fisher information matrix predictions and those from Monte Carlo simulations are in very good agreement above a SNR of 20. We repeat the experiments for equal mass cases, namely a (1.4, 1.4)M⊙ and a (5, 5)M⊙ system. We found a systematic disagreement by a factor of 2 even at large SNRs (errors from the Fisher information matrix being higher). We have shown that by using templates with the symmetric mass ratio η > 0.25, the systematic disagreement vanishes in the regime of SNRs greater than 20.

Comparison of self-administered University of California, Los Angeles, shoulder score with traditional University of California, Los Angeles, shoulder score completed by clinicians in assessing the outcome of rotator cuff surgery

To determine whether the University of California, Los Angeles (UCLA) shoulder score completed by the patient is comparable to that obtained by the clinician, 110 patients who had undergone either arthroscopic subacromial decompression (ASD) or rotator cuff repair (RCR) completed the UCLA score questionnaire by mail at 2 months (ASD subgroup) or 4 months (RCR subgroup). Patients were then assessed by 2 clinicians in random order. There was a very good level of agreement for the overall UCLA score for the total cohort (N = 100 with complete data) (intraclass correlation coefficient [ICC], 0.910; 95% confidence interval [CI], 0.87 to 0.94) and for ASD (n = 46) (ICC, 0.951; 95% CI, 0.92 to 0.97) and good agreement for RCR (n = 54) (ICC, 0.734; 95% CI, 0.61 to 0.83). Agreement between patient and assessor 1, patient and assessor 2, and assessors 1 and 2 was also very good (with whole-cohort ICCs of 0.875, 0.910, and 0.935, respectively). Bland-Altman plots showed little systematic disagreement and consistently narrow limits of agreement. Patient self-administration of the UCLA shoulder score yields acceptable results.

Assessing pain perception using the Painmatcher® in patients with whiplash-associated disorders

To evaluate the Painmatcher, in terms of reliability, and to explore the relationship between pain magnitude matching and pain threshold assessments in patients with whiplash-associated disorders. Also, to investigate gender differences in pain thresholds and explore the correlation between pain-related cognitions and pain threshold. A test-retest study. Forty-seven patients with whiplash-associated disorders. A visual analogue scale and a Painmatcher (an instrument for comparing pain magnitude) were used to evaluate pain intensity. Pain threshold was assessed using the Painmatcher. Pain-related cognitions were assessed using the Painometer and the Tampa Scale for Kinesiophobia. The Painmatcher demonstrated reliable pain magnitude matching scores, but the pain threshold assessment indicated a systematic disagreement. Women exhibited significantly lower pain thresholds than men (p < 0.01). There was a weak but significant correlation between the pain intensity according to the visual analogue scale and the Painmatcher (r = 0.46) (p < 0.01). There was a significant correlation between the emotional experience of pain and pain threshold (r = -0.33) (p < 0.001), but no significant correlation between fear of movement/(re)injury and pain threshold. Measuring pain with the Painmatcher is a reliable method, but may include a possible bias in threshold assessments and seems to be associated with unpleasantness.

The Ly α and Ly β Profiles in Solar Prominences and Prominence Fine Structure

Ly α and Ly β line profiles in a solar prominence were observed with high spatial and spectral resolution with SOHO/SUMER. Within a 60-arcsec scan, we measure a very large variety of profiles: not only reversed and nonreversed profiles but also red-peaked and blue-peaked ones in both lines. Such a spatial variability is probably related to both the fine structure in prominences and the different orientations of mass motions. The usage of integrated-intensity cuts along the SUMER slit allowed us to categorize the prominence in three regions. We computed average profiles and integrated intensities in these lines in the range 2.36 – 42.3 W m−2 sr−1 for Ly α and 0.027 – 0.237 W m−2 sr−1 for Ly β. As shown by theoretical modeling, the Ly α/Ly β ratio is very sensitive to geometrical and thermodynamic properties of fine structure in prominences. For some pixels, and in both lines, we found agreement between observed intensities and those predicted by one-dimensional models. But a close examination of the profiles indicated a rather systematic disagreement concerning their detailed shapes. The disagreement between observations and thread models (with ambipolar diffusion) leads us to speculate about the importance of the temperature gradient between the cool and coronal regions. This gradient could depend on the orientation of field lines as proposed by Heinzel, Anzer, and Gunar (Astron. Astrophys. 442, 331, 2005).

The Conceptions of Pain and Rehabilitation Questionnaire (CPRQ): development and test of face validity and stability over time

The heterogeneity of diagnoses included in the concept of chronic pain, as well as differences in adaptation to the situation involving chronic illness, imply the need for a variety of rehabilitation forms. Despite evidence concerning the success of multidisciplinary behaviour-orientated rehabilitation programmes, not all participants experience the expected change. The aim of the present study was to develop and test the face validity and the stability over time of a Swedish self-administered questionnaire: the Conceptions of Pain and Rehabilitation Questionnaire (CPRQ) for persons with chronic pain. The questionnaire is to be used as a guiding tool in planning for rehabilitation. Its purpose is to distinguish between individuals with expectations of and motivation for active rehabilitation and those with expectations of more supportive forms of therapy. The face validity was mainly obtained by target-group discussions including persons with chronic pain and rehabilitation staff with experience in the rehabilitation of persons with chronic pain. The test–retest stability analysis was performed using a model for identifying occasional and systematic disagreement. The questionnaire in its final form showed face validity and reliability in terms of stability over time. Further steps in the development process will include laying down the guiding principles for the questionnaire, based on new focus-group discussions, and completing work on the manual by including information about the origin of the questionnaire and instructions for its administration. Thereafter, the next step in the development process will be a test of responsiveness, i.e. to examine the degree to which the questionnaire really serves its purpose.

Happy pigs are dirty! – conflicting perspectives on animal welfare

The study of animal welfare cannot be based entirely on science. For a number of assumptions of an ethical nature will it inevitably enter the study of how good or bad animals fare under different systems of animal production. In some cases, ethical assumptions may be uncontroversial, but they may also be the cause of disagreement. A case study is presented that seems to indicate that there is systematic disagreement between lay and expert views about what a good animal life is. The study is based on interviews about modern pig production. The title of this paper summarises the reaction of an interviewee when commenting on pictures of what is generally regarded as animal-friendly pig production. In the lay perspective, living a natural life is an important part of animal welfare – a part that supplements, and therefore needs to be combined with, the absence of suffering and frustration that are central components of the expert approach. The main message of the paper for those who are professionally involved in animal production is that ethical assumptions and potential conflicts of view should be recognised and brought into the discussion of animal welfare.

The 3He(4He, γ)7Be underground experiment at LUNA

The LUNA collaboration, aimed to the direct measurement of nuclear cross sections interesting for the astrophysics with an underground accelerator, is presently working on a new experiment; the study of the 3He(4He, γ)7Be reaction counting both the prompt γ emission and the delayed 7Be activity. So far, several groups have studied this reaction ([1, 2] and references therein) collecting two sub-sets of results (i.e. experiments on prompt and delayed γ counting) which show a systematic disagreement of about 11%. Recent and precise determinations of solar neutrinos flux [3] require a further investigation of the 3He(4He, γ)7Be cross section at the lowest possible energy with an accuracy better of 4%.

Evaluating the reliability of multi-item scales: A non-parametric approach to the ordered categorical structure of data collected with the Swedish version of the Tampa Scale for Kinesiophobia and the Self-Efficacy Scale

To compare the ability of a rank-invariant non-parametric method with that of kappa statistics to evaluate the reliability of the Swedish version of the Tampa Scale for Kinesiophobia and the Self-Efficacy Scale by identifying systematic and random disagreement. The aim was, further, to compare 2 different statistical approaches to obtain a global value from multi-item scales. A test-retest study. A total of 46 patients with whiplash-associated disorders were enrolled and 39 (85%) completed the test-retest assessment. Data from the multi-item scales were summarized using both sum and median scores. Paired data were evaluated with a rank-invariant statistical method to identify systematic and random disagreement. Data were also evaluated with kappa statistics. The non-parametric approach demonstrated that the Swedish version of the Tampa Scale for Kinesiophobia and the Self-Efficacy Scale are reliable for patients with whiplash-associated disorders. In contrast to the rank-invariant method, kappa statistics provided no information on disagreement between the 2 test occasions. Median scoring improved reliability due to lack of disagreement while the sum scores method was characterized by random individual disagreement. This study has increased understanding of the advantages and limitations of 2 non-parametric statistical methods and, it is hoped, will contribute to the development of reliable measurements.

Axial-symmetric transmission gauge: Extension of its pressure measuring range and reduction of the electron stimulated desorption ion effect in ultrahigh vacuum

The basic characteristics of the axial-symmetric transmission gauge (AT gauge), that were modified for measurement over a wide pressure range, are reported. A Faraday cup ion collector is used instead of a secondary electron multiplier to extend the measurable pressure range to 10−3Pa. The sensitivity of the gauge was determined by a conductance modulation method, and by direct comparison against an extractor gauge and a spinning rotor gauge as well. When operating in O2, there was systematic disagreement between pressure readings with the AT gauge and the extractor gauge. This is due to the difference in the elimination efficiency of the electron stimulated desorption ion.

Quantitative assessment of uncertainties for a model of tropospheric ethene oxidation using the European Photoreactor (EUPHORE)

Methods of uncertainty analysis were used for comparison of the Master Chemical Mechanism version 3 (MCMv3) with measurements made in the European Photoreactor (EUPHORE) at Valencia (Spain) to investigate model–measurement discrepancies and to obtain information on the importance of wall effects. Two EUPHORE smog chamber measurements of ethene oxidation, under high and low NOx conditions were analysed by the following methods: (i) local uncertainty analysis, (ii) the global screening method of Morris and (iii) Monte Carlo (MC) analysis with Latin hypercube sampling. For both experiments, ozone (by 25% and 30%, respectively) and formaldehyde (by 34% and 40%, respectively) are significantly over-predicted by the model calculations, while the disagreement for other species is less substantial. According to the local uncertainty analysis and the Morris method, the most important contributor to ozone uncertainty under low NOx conditions is HOCH2CH2O2+NO→HOCH2CH2O+NO2, while under high NOx conditions OH+NO2→HNO3 is the main contributor. The MC simulations give an estimate of the 2σ uncertainty for ozone as ∼20% in both scenarios at the end of the experiment. The results suggest systematic disagreement between measurements and model calculations, although the origin of this is not clear. It seems that chamber effects alone are not responsible for the observed discrepancies.

Recent Issues Regarding rWG, rWG, rWG(J), and rWG(J)

A recent article by Lindell and Brandt raised two concerns regarding the use of James, Demaree, and Wolf’s interrater agreement indices rWG and rWG(J). First, they noted that the multi-item rWG(J) equation is mathematically equivalent to inserting rWG into the Spearman-Brown prophecy formula and questioned whether applying a formula developed for a reliability index was also appropriate for an agreement index. Second, they questioned the appropriateness of James et al.’s suggestion of replacing obtained negative values of rWG with zeros. This article addresses these concerns by demonstrating that rWG(J) can be derived independently from the Spearman-Brown prophecy formula and that negative values of rWG can be avoided by reparameterizing the structural equation underlying the data when there is systematic disagreement between subgroups of raters.

Evaluation of variations in sensory and pain threshold assessments by electrocutaneous stimulation

Assessed sensory and pain thresholds can change consequently to disturbances associated with ongoing pain. Such assessments could be an additional method in the daily clinical evaluation of perceived pain. To study the test–retest variability within-day and between-day of such procedures a newly developed instrument producing electrocutaneous stimulation, PainMatcher (PM), was used to assess the electrical sensory thresholds (EST) and pain thresholds (EPT) in healthy volunteers and in patients with pain. The produced data were considered ordinal and analyzed with rank-invariant statistics with properties of analyzing systematic disagreement, bias, and individual variations.The percentage agreements within ±1PM value for EST were in the two groups of healthy volunteers and patients in pain 94% and 92%, and for EPT assessments 49% and 78%, respectively. The variability in the EST assessments is possibly explained by a slight bias while the individual variations were negligible between the two occasions. The assessed EPT were unbiased in both groups while individual variations were significant among the healthy volunteers but negligible among the patients in pain. The EST was found to be increased in pain patients compared to healthy volunteers, p < 0.03, and the EPT decreased in pain patients compared to healthy volunteers, p < 0.001.The results in this study indicate stable and reliable assessments of EST and EPT except for a possible bias. The threshold assessment procedure followed in this study may be a valuable tool in the clinical evaluation of sensory and pain assessments in pain patients.

Paleomagnetism of Upper Triassic rocks in the Los Colorados hill section, Mendoza province, Argentina

Different authors have highlighted a systematic disagreement between Late Carboniferous–Triassic paleomagnetic poles (PPs) for Gondwanaland and Laurasia when they are repositioned in a classical reconstruction prior to the breakup of Pangea A. This disagreement has been interpreted in geodynamic terms or as an evidence of non-dipole components of the geomagnetic field. Such analyses have been made using data on South American PPs published approximately 25 years ago and obtained using outdated methodologies. In this article, the authors present new Late Triassic paleomagnetic data from rocks that crop out in the Pre-Andean ranges (Precordillera) of Mendoza province (Argentina). Samples of different lithologies were taken from two limbs of a doubly plunging syncline, and several field tests of paleomagnetic stability were applied. The results indicate primary site mean directions that yield a PP with geographic coordinates and statistical parameters as follows: Lat.=76°S, Lon.=280°E, N=12, R=11.63, α 95=8°, K=30.2. This PP agrees with mean PPs of Laurasia of similar ages in different models of Pangea A, indicating that the hypothesis of a dipolar paleomagnetic field could be valid for the Late Triassic.

Measurement of Differential Thick-Target Neutron Yields of C, Al, Ta, W(p,xn) Reactions for 50-MeV Protons

Energy-angular differential thick-target neutron yields were measured at 50 MeV for the C, Al, Ta, W(p,n) reactions with a time-of-flight (TOF) method using the Tohoku University K = 110-MeV cyclotron equipped with a beam-swinger system and a well-collimated TOF line. Neutron spectrum data have been obtained down to ~0.8 MeV from the highest energy by use of two different experimental setups to extend the dynamic range of the energy range. Data were obtained at six laboratory angles from 0 to 90 deg. The results are compared with the recent data library LA150. LA150 reproduces the general trend of the experimental data fairly well but still shows marked systematic disagreement in particular in high-energy regions.

High-Resolution Infrared Spectroscopy of the Brown Dwarf Indi Ba

We report on the analysis of high-resolution infrared spectra of the newly discovered brown dwarf Ind Ba. This is the closest known brown dwarf to the solar system, with a distance of 3.626 pc. Spectra covering the ranges of λλ2.308-2.317 μm and λλ1.553-1.559 μm were observed at a resolution of λ/Δλ = R = 50,000. The physical parameters of effective temperature and surface gravity are derived for Ind Ba by comparison with model spectra calculated from atmospheres computed using unified cloudy models. The results are Teff = 1500 ± 100 K, log g = 5.2 ± 0.3 (in units of cm s-2), placing it in the critical boundary between the late L and early T dwarfs. The high spectral resolution also allows us to measure an accurate projected rotational velocity, with v sin i = 28 ± 3 km s-1. Combined with a published luminosity for Ind Ba [with log(L/L☉) = -4.71], the derived parameters result in a spectroscopic mass estimate of ~30MJ, a radius of ~0.062 R☉, and a maximum rotational period of ~3.0 hr. A compilation and comparison of effective temperatures derived from spectroscopy using model atmospheres versus those derived from luminosities and theoretical Mbol-radius relations reveal a systematic disagreement in the Teff scale. The source of this disagreement is unknown.

Perceptual Matching for Assessment of Itch; Reliability and Responsiveness Analyzed by a Rank-Invariant Statistical Method

The aim of this study was to evaluate the reliability and responsiveness of a new device-perceptual matching by Matcher (Cefar Medical AB, Lund, Sweden)-in the assessment of the progress of experimentally induced itch as well as determine the reliability of the method in patients with skin disease and itch. The perceptual matching unit electrically stimulates the skin of the fingers in the left hand. When the amplitude of the sensation corresponded to that of the experienced itch, the subject was instructed to halt the stimulation and a value was automatically saved in the electronic device. A total of 36 healthy subjects and nine patients participated in the study. The healthy subjects were asked to rate the level of itch every 30 s during the first 5 min and thereafter every minute. The reliability was determined in a test-retest procedure of the time points 5, 10, and 15 min after induction of itching. To test the stability of the method, the first sensation of pain in healthy subjects without itch was determined every 10th minute during 60 min. In patients, the test-retest procedure was repeated within 5 min. Perceptual matching was found to be a reliable method of itch assessment, with no evidence for random individual disagreement between the assessments. The augmented rank order coefficient ra was excellent: 1.00 at 5 min; 0.99 at 10 min; and 1.00 at 15 min. There was a clear indication of responsiveness for detecting changes in itch over time, p<or=0.05. The perceptual matcher device can detect immediate changes in perceived itch and is also sensitive to gradual decreases after the induction of itch. The first sensation of pain in healthy subjects without itch was unaffected when assessed every 10th minute during 60 min. In patients, no evidence for random disagreement or systematic disagreement by group between repeated assessments was detected. The augmented rank order coefficient was high (0.98). In conclusion, Matcher measures itch intensity via perceptual matching with a high reliability and excellent responsiveness. The method is stable and can be recommended as an assessment tool for itch intensity both in experimental conditions as well as in patients with skin disease and itch.

Perceptions and reasons for choice of fat- and fibre-containing foods by Swedish schoolchildren

This study investigated schoolchildren's breakfast choices focusing on their reported usual intake and perceptions of fat-reduced or fibre-enriched alternatives. A total of 184 eleven- to fifteen-year-old were asked to participate, and 181 completed the study. Using pictures of food items, the children were instructed to reproduce their usual breakfast, and then breakfasts that would be: healthy, tasty, consumed by their parents, or approved by their parents. Participants' usual breakfast included breads and breakfast cereals containing a higher fibre content than that of the breakfast reported as most palatable. Their usual breakfast also contained products with less fibre than was the case for their healthy or perceived parental norm breakfasts. This may be interpreted as evidence that high-fibre bread and breakfast cereals are perceived as healthy but that consumption of these products is limited by palatability. In contrast to the ambivalence towards cereal products, corresponding disagreements between breakfasts were not observed for milk, and only a small systematic disagreement was observed for spread. Thus, the majority consumed the kind of milk and spread perceived as being healthy, tasty and parentally sanctioned despite the fact that full-fat products were frequently consumed. In conclusion, the results suggest that taste may be a barrier to consumption of high-fibre products, while consumption of low-fat products appears to be impeded by health beliefs.