A comparison of traceable spatial angle autocollimator calibrations performed by PTB and VTT MIKES

Autocollimators are versatile devices for angle metrology used in a wide range of applications in engineering and manufacturing. A modern electronic autocollimator generally features two measuring axes and can thus fully determine the surface normal of an optical surface relative to it in space. Until recently, however, the calibration capabilities of the national metrology institutes were limited to plane angles. Although it was possible to calibrate both measuring axes independently of each other, it was not feasible to determine their crosstalk if angular deflections were present in both axes simultaneously. To expand autocollimator calibrations from plane angles to spatial angles, PTB and VTT MIKES have created dedicated calibration devices which are based on different measurement principles and accomplish the task of measurand traceability in different ways. Comparing calibrations of a transfer standard makes it possible to detect systematic measurement errors of the two devices and to evaluate the validity of their uncertainty budgets. The importance of measurand traceability via calibration for a broad spectrum of autocollimator applications is one of the motivating factors behind the creation of both devices and for this comparison of the calibration capabilities of the two national metrology institutes. The latter is the focus of the work presented here.

Improving the Stability of the Directional Room G 31-33, Horizon 210 - East, Ocnele Mari-Coceneṣti Salt Mine, By Reinforcement with Anchors and Shotcrete

The rock salt deposit from Ocnele Mari - Coceneşti was mined by the method with rooms and small square pillars, at the levels + 226m and + 210m. Although the saline is not deep, certain instability phenomena (cracks, exfoliations) have occurred in the resistance structures (pillars, ceilings), especially in the G31-33 directional room, horizon 210E. These instability phenomena were also highlighted following the 3D finite element numerical modelling. In order to prevent the degradation of the mining excavations and the resistance structures, the affected surfaces were supported with anchors and reinforced shotcrete. The ceiling of the consolidated section of the G31-33 directional room, horizon 210E is monitored by the systematic measurement, on topographic landmarks mounted on the ceiling, of the vertical and horizontal displacements.

Identifying and Minimizing Errors in the Measurement of Early Childhood Development: Lessons Learned from the Cognitive Testing of the ECDI2030

Challenges in measuring early childhood development (ECD) at scale have been documented, yet little is known about the specific difficulties related to questionnaire design and question interpretation. The purpose of this paper is to discuss the challenges of measuring ECD at scale in the context of household surveys and to show how to overcome them. The paper uses examples from the cognitive interviewing exercises that were conducted as part of the methodological work to develop a measure of ECD outcomes, the ECDI2030. It describes the methodological work carried out to inform the selection and improvement of question items and survey implementation tools as a fundamental step to reduce and mitigate systematic measurement error and improve data quality. The project consisted of a total of five rounds of testing, comprising 191 one-on-one, in-depth cognitive interviews across six countries (Bulgaria, India, Jamaica, Mexico, Uganda, and the USA). Qualitative data analysis methods were used to determine matches and mismatches between intention of items and false positives or false negative answers among subgroups of respondents. Key themes emerged that could potentially lead to systematic measurement error in population-based surveys on ECD: (1) willingness of child to perform task versus ability of child to perform task; (2) performing task versus performing task correctly; (3) identifying letters or numbers versus recognizing letters or numbers; (4) consistently performing task versus correctly performing task; (5) applicability of skills being asked versus observability of skills being asked; and (6) language production versus language comprehension. Through an iterative process of testing and subsequent revision, improvements were made to item wording, response options, and interviewer training instructions. Given the difficulties inherent in population-level data collection in the context of global monitoring, this study’s findings confirm the importance of cognitive testing as a crucial step in careful, culturally relevant, and sensitive questionnaire design and as a means to reduce response bias in cross-cultural contexts.

Age is measured with systematic measurement error in developing country surveys: A diagnosis and analysis of consequences

Research in political science and other social sciences often relies on survey data to study a range of questions about politics in the developing world. This study identifies systematic measurement error in some of the most frequently used datasets with respect to one commonly employed variable: respondent’s age. It shows evidence of substantial measurement error that is correlated with observable characteristics, and discusses and illustrates the implications for empirical analysis with an example from a recently published study. In doing so, it demonstrates tools for identifying and diagnosing systematic measurement error in survey data, as well as for investigating the robustness of one’s findings when the problem arises.

Concurrent Validity and Reliability of Manual Versus Specific Device Transcostal Measurements for Breathing Diaphragm Thickness by Ultrasonography in Lumbopelvic Pain Athletes

The use of rehabilitative ultrasound imaging (RUSI) to evaluate diaphragm thickness during breathing in athletes who suffer from non-specific lumbopelvic pain presents some measurement errors. The purpose of this study was to evaluate intra- and inter-sessions, intra- and inter-rater reliabilities, and concurrent validity of diaphragm thickness measurements during breathing using transcostal RUSI with a novel thoracic orthotic device that was used to fix the US probe versus those measurements obtained using manual fixation. A total of 37 athletes with non-specific lumbopelvic pain were recruited. Intra- (same examiner) and inter-rater (two examiners) and intra- (same day) and inter-session (alternate days) reliabilities were analyzed. All measurements were obtained after manual probe fixation and after positioning the thoracic orthotic device to fix the US probe in order to correctly correlate both measurement methods. Both left and right hemi-diaphragm thickness measurements were performed by transcostal RUSI at maximum inspiration, expiration, and the difference between the two parameters during relaxed breathing. Intra-class correlation coefficients (ICC), standard errors of measurement (SEM), minimum detectable changes (MCD), systematic errors, and correlations (r) were assessed. Orthotic device probe fixation showed excellent reliability (ICC = 0.852–0.996, SEM = 0.0002–0.054, and MDC = 0.002–0.072), and most measurements did not show significant systematic errors (p > 0.05). Despite manual probe fixation with a reliability ranging from good to excellent (ICC = 0.714–0.997, SEM = 0.003–0.023, and MDC = 0.008–0.064 cm), several significant systematic measurement errors (p < 0.05) were found. Most significant correlations between both orthotic device and manual probe fixation methods were moderate (r = 0.486–0.718; p < 0.05). Bland–Altman plots indicated adequate agreement between both measurement methods according to the agreement limits. The proposed novel thoracic orthotic device may allow ultrasound probe fixation to provide valid and reliable transcostal RUSI measurements of diaphragmatic thickness during relaxed breathing thus reducing some measurement errors and avoiding systematic measurement errors. It may be advisable to measure diaphragm thickness and facilitate visual biofeedback with respect to diaphragm re-education during normal breathing in athletes with non-specific lumbopelvic pain.