In general, individual samples which are composited must be the same size or volume and the composite sample must be completely mixed. The entire composite sample may be measured for desired information, or one or more random sub-samples may be measured individually. Sampling method used where several samples are physically mixed into a larger composite sample. EPA 2016)Ī measure of the amount of valid data obtained from a measurement system compared with the amount that was expected to be obtained under correct, normal conditions. Comparability for sampling primarily involves sampling designs and time periods, while analytical comparability focuses on whether different laboratories were used, the units of measure, and sample preparation procedures. Comparability describes the confidence that two data sets can contribute to a common analysis and interpolation. The degree to which different methods or data agree or can be represented as similar. This sampling approach ensures that samples are collected from locations perceived as most likely to be contaminated (through targeted samples) while protecting against the possibility that contamination may exist in less likely areas (through probabilistic samples). Uses Bayesian statistical methodology to combine results from targeted and probabilistic samples to make statistical confidence statements.
EPA 2018d)Ĭombined Targeted and Probabilistic Sampling The information that results from the characterization affects and shapes the planning and implementation of the remediation phase. The data will be evaluated and reviewed, and used to assist in formulating the objectives, strategy, and approach for the characterization phase. The sampling information, specifics of the incident, and the data collected during the initial assessment might take on many forms and might come from several different groups involved in the initial response and assessment activities. Characterization systematically expands on the initial assessment findings to identify other contaminated locations and determine the contamination footprint at the affected locations, in order to better define the boundaries. Also documents all analyses that were performed on the samples.Īssessment of the extent, location, and magnitude of contamination. Provides a chronological record of who has possessed the sample(s) from the moment of collection through receipt in the laboratory, to the eventual destruction or disposal.
Expressing a positive analytical measurement falling below the LOQ as less than the established quantification limit or expressing a non-detect result as less than the detection limit. The levels of calibration standards should bracket the range of levels for which actual measurements are to be made.ĭata that includes both detected and non-detected results.
The comparison of a measurement standard or instrument with another standard or instrument to report or eliminate, by adjustment, any variation (deviation) in accuracy of the item being compared. The systematic or persistent distortion of a measurement process which deprives the result of representativeness (i.e., the expected sample measurement is different than the sample's true value.) A data quality indicator.ĭata that can only have two possible values. Airborne transmission allows organisms to enter the upper and lower respiratory tracts. These organisms must be capable of surviving for long periods of time outside the body and must be resistant to drying. Situations where droplet nuclei (residue from evaporated droplets) or dust particles containing microorganisms can remain suspended in air for long periods of time. Accuracy includes random error (precision) and systematic error (bias or recovery) that are caused by sampling and analysis. The degree of agreement between an observed value and an accepted reference value.
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