Which of the following actions will contribute to a nonrepresentative sample?

Ignoring sample size specifications can indeed lead to a nonrepresentative sample. When conducting sampling, it is crucial to adhere to specified sample sizes, as not following these guidelines can result in an inadequately sized sample that may not accurately reflect the characteristics of the larger population being studied. A small sample size, for instance, might miss variability in material properties, leading to skewed or incorrect conclusions regarding the overall quality or composition of the aggregate base.

In contrast, the other actions listed actively promote representative sampling. Methodical sampling ensures that samples are taken consistently and systematically, thereby capturing variability. Using clean tools prevents contamination, which could alter the properties of the sample. Finally, following established sampling procedures ensures that the methods employed are recognized as effective for obtaining representative samples, thus enhancing the validity of the results.