Meranie je súhrn činností s cieĺom určiť hodnotu meranej veličiny. Táto hodnota by sa mala uvádzať spolu s toleranciou, v ktorej leží pravá hodnota meranej veličiny, prípadne toĺkými číslami, koĺko odpovedá platným miestam výsledku merania. To je dôležité najmä v súčasnosti, keď sa pre spracovanie výsledkov používajú počítače pracujúce s číslami s veĺkým počtom miest. Žiadnym meraním nezískame správnu hodnotu meranej veličiny, pretože každé meranie je zaťažené chybou. Chyba charakterizuje presnosť merania. Účelom štúdia chýb je zistenie celkovej chyby, jej čiastkových zložiek a ich príčin. Analýza chýb je základnou podmienkou zvyšovania presnosti merania. Výsledok merania je neúplný, pokiaĺ neobsahuje možný rozsah chýb., Miroslav Gutten, Ján Michalík, Jozef Kúdelčík., and Obsahuje seznam literatury
A portable open gas-exchange system (Li-6400, Li-Cor, Inc., Lincoln, NE, USA) has been widely used for the measurement of net gas exchanges and calibration/parameterization of leaf models. Measurement errors due to diffusive leakage rates of water vapor (LW) and CO2 (LC) between inside and outside of the leaf chamber, and the inward dark transpiration rate (DW) and dark respiration rate (DC) released from the leaf under the gasket, can be significant. Rigorous model-based approaches were developed for estimating leakage coefficients of water vapor (KW) and CO2 (KC) and correcting for the combination of these errors. Models were based on mass balance equations and the Dusty Gas Model for a ternary gas mixture of water vapor, CO2, and dry air. Experiments were conducted using two Li-6400 systems with potato and soybean leaves. Results indicated that models were reliable for estimating KW and KC, and the values varied with instrument, chamber size, gasket condition, and leaf structure. A thermally killed leaf should be used for this determination. Measurement error effects on parameterization of the Farquhar et al. (1980) model as determined by PN/C i curves were substantial and each parameter had its own sensitivity to measurement errors. Results also indicated that all four error sources should be accounted for when correcting measurements., Q. Wang ... [et al.]., and Obsahuje bibliografii a dodatky
In this paper a new rank test in a linear regression model is introduced. The test statistic is based on a certain minimum distance estimator, however, unlike classical rank tests in regression it is not a simple linear rank statistic. Its exact distribution under the null hypothesis is derived, and further, the asymptotic distribution both under the null hypothesis and the local alternative is investigated. It is shown that the proposed test is applicable in measurement error models. Finally, a simulation study is conducted to show a good performance of the test. It has, in some situations, a greater power than the widely used Wilcoxon rank test.
The aim of this article is to provide an overview of the problems associated with the fielding of questions of a socially sensitive nature typically dealing with crime, health, and sexual activity in nationally representative sample surveys. This article presents an overview of previous research on this topic and associated themes such as the definition of sensitive survey questions, the emergence and impact of social desirability effects and application of the Cognitive Aspects of Survey Methodology (CASM) to mechanisms of question response on sensitive topics. Thereafter, this article maps out specific sources of error that are likely to occur when fielding sensitive survey questions; and highlights methods that may used to minimise measurement error, thereby enhancing data validity. The article concludes with an appraisal of some of the most influential criterion-validity used in this sub-field of survey research., Johana Chylíková., and Obsahuje bibliografii a bibliografické odkazy
The aim of this article is to provide an overview of the problems associated with the fielding of questions of a socially sensitive nature typically dealing with crime, health, and sexual activity in nationally representative sample surveys. This article presents an overview of previous research on this topic and associated themes such as the definition of sensitive survey questions, the emergence and impact of social desirability effects and application of the Cognitive Aspects of Survey Methodology (CASM) to mechanisms of question response on sensitive topics. Thereafter, this article maps out specific sources of error that are likely to occur when fielding sensitive survey questions; and highlights methods that may used to minimise measurement error, thereby enhancing data validity. The article concludes with an appraisal of some of the most influential criterion-validity used in this sub-field of survey research.