This practice is useful for determining the location or time, or both, to take a sample in order to minimize any unintentional bias on the part of the person taking the sample.
Note 18212;The effectiveness of this practice in achieving random samples is limited only by the conscientiousness of the user in following the stipulated procedures.
The selection procedures and examples in this standard provide a practical approach for ensuring that construction material samples are obtained in a random manner. Additional details concerning the number of sample increments, the number of samples, the quantities of material in each, and the procedures for extracting sample increments or samples from the construction lot or process are contained in Practices C172, C183, D75, D140, D979, D5361, and Test Method D345.
This standard contains examples citing road and paving materials. The concepts outlined herein are applicable to the random sampling of any construction material and can easily be adapted thereto.
Additional sampling guidance is provided in Practice E105 concerning probability sampling, Practice E122 concerning choosing sample sizes to estimate the average quality of a lot or process (see Note 2), and in Practice E141 for acceptance of evidence based on results of probability sampling.
Note 28212;The guidance contained in Practice E122 is not available in other documents referenced in this section.
The best and most practical method for ensuring that samples of construction materials include the full range of a construction process is by incorporating a stratified-random sampling procedure into the sampling process. To implement a stratified-random sampling procedure, divide the lot to be sampled into the desired number of equal sublots and randomly sample each sublot in accordance with this standard.
Note 38212;If the sublots are of unequal size, it will likely be necessary to weight the samples in order to maintain a fair and defensible sampling process.
TABLE 1 Table of Random Numbers
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Row | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | ||||||||||||