Confidence Intervals pollutants

Mean depression in CO2 uptake rates induced after 1-hr exposures, and 95% confidence interval. (Superscripts and denote those significant means at the P.Ol and P.05 levels, respectively, when compared with the summed depressions determined for the separately applied pollutants at corresponding concentrations. )... 

Student s t-test is frequently used in statistical evaluations of environmental chemical data. It establishes a relationship between the mean (x) of normally distributed sample measurements, their sample standard deviation (,v), and the population mean (p). Confidence intervals may be calculated based on Student s t-test (Equation 10). The upper limit of the confidence interval is compared to the action level to determine whether the sampled medium contains a hazardous concentration of a pollutant. If the upper confidence limit is below the action level, the medium is not hazardous otherwise the opposite conclusion is reached. 

Frequentist methods are fundamentally predicated upon statistical inference based on the Central Limit Theorem. For example, suppose that one wishes to estimate the mean emission factor for a specific pollutant emitted from a specific source category under specific conditions. Because of the cost of collecting measurements, it is not practical to measure each and every such emission source, which would result in a census of the actual population distribution of emissions. With limited resources, one instead would prefer to randomly select a representative sample of such sources. Suppose 10 sources were selected. The mean emission rate is calculated based upon these 10 sources, and a probability distribution model could be fit to the random sample of data. If this process is repeated many times, with a different set of 10 random samples each time, the results will vary. The variation in results for estimates of a given statistic, such as the mean, based upon random sampling is quantified using a sampling distribution. From sampling distributions, confidence intervals are obtained. Thus, the commonly used 95% confidence interval for the mean is a frequentist inference... 

The significance of these results cannot be missed. If the confidence interval is based on time, competitive relationships differ on a seasonal basis, and the lack of a species at certain times may not be due to an increase or decrease in pollutants but may be attributable to yearly changes in resource availability. 

Vertrtiglichkeitsmacher/Vemfiittler compatibilizer Vertrauensintervall/ Konfidenzintervall stat confidence interval verunreinigen contaminate, pollute verunreinigt/ schmutzig/unsauber impute, contaminated, polluted Verunreinigung/... 

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