Reference values: a review

Reference values are used to describe the dispersion of variables in healthy individuals. They are usually reported as population-based reference intervals (RIs) comprising 95% of the healthy population. International recommendations state the preferred method as a priori nonparametric determination from at least 120 reference individuals, but acceptable alternative methods include transference or validation from previously established RIs. The most critical steps in the determination of reference values are the selection of reference individuals based on extensively documented inclusion and exclusion criteria and the use of quality-controlled analytical procedures. When only small numbers of values are available, RIs can be estimated by new methods, but reference limits thus obtained may be highly imprecise. These recommendations are a challenge in veterinary clinical pathology, especially when only small numbers of reference individuals are available

Exercise capacity in Dutch children

The Bruce treadmill protocol is suitable for children 4 years of age and older. Dutch reference values were established in 1987. We considered that children's exercise capacity has deteriorated due to changes in physical activity patterns and eating habits. We determined new reference values and evaluated determinants of exercise capacity. Healthy Dutch children (n=267) aged 6-13 years participated in this cross-sectional observational study. The maximal endurance time on the treadmill was the criterion of exercise capacity. Furthermore, we obtained data on anthropometry, smoking habits, socioeconomic status, ethnicity, sports participation, and school transport habits. The maximal endurance time for children aged up till 10 was lower (up to 1.6 and 1.4 min in girls and boys, respectively) than previously published. Body mass index was negatively, and intense sports participation was positively associated with endurance time (β=-0.412 and 0.789, respectively; P<0.001). In conclusion, exercise capacity seems to have deteriorated in Dutch children aged up till 10 years whereas the values from the older children are remarkably similar to those from the previous study

Reference values for railway sidings track geometry

Railway sidings are operated at speeds much lower than those used on national railway lines; a typical speed is 6 km/h. In establishing reference values for maintenance of railway infrastructure in terms of the geometry for such operating conditions, it is noted that both national and European regulations do not provide specific information regarding railway sidings. The overall objective of the research is, therefore, the definition of possible reference values for track geometry, based on those adopted by European rail networks (European and national standards), which can guarantee the appropriate security level for low speed operation typical of railway sidings connected to the national network. The basic principle in defining these values is the maximization of technical-economic efficiency and the maintenance of the acceptability of the risk associated to railway operation. The research results can therefore provide useful information about the cost-effective management of maintenance and safe operation for railway sidings. For this purpose, the approach was inspired to that of Regulation 402/2013, which defines at European level a common safety method for risk analysis. Quantification of probabilities and damages should be based on simulation models because the available statistics do not allow significant results to be inferred. However, the research sector has not yet produced a consolidated modelling. For these reasons, and since it is not possible to quantify probabilities reliably, the proposals resulting from this research are based on the identification of situations where it can be shown that the hazard probability remains unchanged. The approach used to formulate possible reference values valid outside of national networks (railway sidings) is based on an understanding of the underlying principles of the codes of good practice, on the formulation of hypotheses conform to the same principles, and the proposals about mitigative measures of risk associated to the use of different reference values, such as to keep the risk of the railway within the limits of acceptability, acting conservatively so as to keep unchanged, or reduce, the probability of hazardous events.The assessment parameters, object of the first phase of the research referred to in this work and used here as an example, are longitudinal level and alignment of railway track. In the case of vehicles running at low speed, the study was conducted by varying the magnitude of the reference values by using values that belong to external intervals with respect to those in accordance with European and national codes of good practice, examining the corresponding effects on the physical quantities related to safety. The effects of their variations on the wheel-rail interaction forces were studied using a simple dynamic model (with one degree of freedom) and a random generated excitation given by track defectiveness and the corresponding random response in terms of vertical and lateral contact forces (Q and Y)

Income and happiness across Europe: Do reference values matter?

Using data from the European Social Survey (ESS), we examine the link between income and subjective well-being. We find that, for the whole sample of nineteen European countries, although income is positively correlated with both happiness and life satisfaction, reference income exerts a negative effect on individual well-being, a result consistent with the relative utility hypothesis. Performing separate analyses for some Eastern European countries, we also find some evidence of a ‘tunnel effect’, in that reference income has a positive impact on subjective well-being. Our findings support the view that in environments with stable income and employment, reference income serves as a basis for social comparisons, whereas in relatively volatile environments, it is used as a source of information for forming expectations about future status

Income and Happiness across Europe: Do Reference Values Matter?

Using data from the European Social Survey (ESS), we examine the link between income and subjective well-being. We find that, for the whole sample of nineteen European countries, although income is positively correlated with both happiness and life satisfaction, reference income exerts a negative effect on individual well-being, a result consistent with the relative utility hypothesis. Performing separate analyses for some Eastern European countries, we also find some evidence of a ‘tunnel effect’, in that reference income has a positive impact on subjective well-being. Our findings support the view that in environments with stable income and employment, reference income serves as a basis for social comparisons, whereas in relatively volatile environments, it is used as a source of information for forming expectations about future status.comparison income, reference groups, happiness, life satisfaction

Dietary reference values for sodium

Following a request from the European Commission, the EFSA Panel&nbsp;on Nutrition, Novel Foods and Food Allergens (NDA) derived dietary reference values (DRVs) for sodium. Evidence from balance studies on sodium and on the relationship between sodium intake and health outcomes, in particular cardiovascular disease (CVD)-related endpoints and bone health, was reviewed. The data were not sufficient to enable an average requirement (AR) or population reference intake (PRI) to be derived. However, by integrating the available evidence and associated uncertainties, the Panel&nbsp;considers that a sodium intake of 2.0&nbsp;g/day represents a level of sodium for which there is sufficient confidence in a reduced risk of CVD in the general adult population. In addition, a sodium intake of 2.0&nbsp;g/day is likely to allow most of the general adult population to maintain sodium balance. Therefore, the Panel&nbsp;considers that 2.0&nbsp;g sodium/day is a safe and adequate intake for the general EU population of adults. The same value applies to pregnant and lactating women. Sodium intakes that are considered safe and adequate for children are extrapolated from the value for adults, adjusting for their respective energy requirement and including a growth factor, and are as follows: 1.1&nbsp;g/day for children aged 1\u20133&nbsp;years, 1.3&nbsp;g/day for children aged 4\u20136&nbsp;years, 1.7&nbsp;g/day for children aged 7\u201310&nbsp;years and 2.0&nbsp;g/day for children aged 11\u201317&nbsp;years, respectively. For infants aged 7\u201311&nbsp;months, an Adequate Intake (AI) of 0.2&nbsp;g/day is proposed based on upwards extrapolation of the estimated sodium intake in exclusively breast-fed infants aged 0\u20136&nbsp;months