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A sampling frame is often defined as a list of elements of the population we want to explore through a sample survey. A slightly more general concept considers that a sampling frame is a tool that allows the identification and access to the elements of the population, even if an explicit list does not exist. [1] Traditional sampling frames are ...
For example, the ionic strength of the solution can have an effect on the activity coefficients of the analytes. [3] [4] The most common approach for accounting for matrix effects is to build a calibration curve using standard samples with known analyte concentration and which try to approximate the matrix of the sample as much as possible. [2]
In statistics, a sampling frame is the source material or device from which a sample is drawn. [1] It is a list of all those within a population who can be sampled, and may include individuals, households or institutions. [1] Importance of the sampling frame is stressed by Jessen [2] and Salant and Dillman. [3]
The most common form of systematic sampling is an equiprobability method. [1] This applies in particular when the sampled units are individuals, households or corporations. When a geographic area is sampled for a spatial analysis, bi-dimensional systematic sampling on an area sampling frame can be applied. [2]
An example of cluster sampling is area sampling or geographical cluster sampling.Each cluster is a geographical area in an area sampling frame.Because a geographically dispersed population can be expensive to survey, greater economy than simple random sampling can be achieved by grouping several respondents within a local area into a cluster.
The remainder of the sample is called the matrix. The procedure of analysis measures the analyte's chemical or physical properties, thus establishing its identity or concentration in the sample. The procedure of analysis measures the analyte's chemical or physical properties, thus establishing its identity or concentration in the sample.
When working with limiting amount of sample, an analyst might need to make a single addition, but it is generally considered a best practice to make at least two additions whenever possible. [5] Note that this is not limited to liquid samples. In atomic absorption spectroscopy, for example, standard additions are often used with solid as the ...
In analytical chemistry, sample preparation (working-up) refers to the ways in which a sample is treated prior to its analyses. Preparation is a very important step in most analytical techniques, because the techniques are often not responsive to the analyte in its in-situ form, or the results are distorted by interfering species .