Pouring off the top few pounds from a field sample to produce a test portion will ensure the test portion represents the field sample.

• A. True
• B. It depends on sample size
• C. False
• D. Only if sample is homogeneous

Answer: (C)

Representativeness comes from a mixed, composite view of the whole field sample, not from a single portion. In practice, field samples are not perfectly uniform; different layers or areas can have different particle sizes, binder content, moisture, or other characteristics. If you pour off only the top few pounds, you’re selecting material that may be biased by what sits on top, leaving out portions of the sample that contribute to the overall makeup. That top portion won’t reliably reflect the entire field sample.

To get a test portion that truly represents the field sample, you should thoroughly mix the entire sample or obtain multiple incremental samples from different parts of the material and combine them, using proper sampling techniques (splitting, quartering, etc.). Only in an ideal, perfectly homogeneous sample would the top portion mirror the whole, which is not something you can rely on in real-world field samples.