Overview of the number of sampling units and subsamplesIn theory, the number of typefaces taken from a batch of coal in order to obtain a specific sampling precision is a function of the quality variability of the batch of coal, regardless of the amount of coal in the batch. A batch of coal can be used as a whole sampling unit, and each sampling unit takes a total sample.
For the following purposes, a batch of coal should be divided into several sampling units:
a) Improve the precision of sampling to achieve the required value;
b) maintaining the integrity of the sample, that is, avoiding bias after the sample is taken, especially reducing the loss of moisture due to the sample being placed;
c) when the sampling period is long, it is easy to manage;
d) Make the sample quantity not too large, which is easy to handle.
The number of sampling units and the number of subsamples of each sampling unit are determined according to 18.104.22.168 and 22.214.171.124.