Which of the following is NOT a result taken from a test sample?

Thermal stability is not typically evaluated as a direct result obtained from a test sample in the same way as the other options mentioned. Compressive strength is a fundamental property measured to determine how well a material can withstand compressive forces, making it a standard outcome of testing on refractory materials. Linear change measures dimensional stability under varying temperatures or conditions, which is also crucial for assessing the longevity and reliability of refractory materials. Erosion resistance, on the other hand, is directly assessed by subjecting a sample to conditions that simulate its operational environment, observing how well it withstands abrasive forces.

In contrast, thermal stability is often considered more of a characteristic of the material related to its behavior at elevated temperatures rather than a quantifiable result derived from a specific test sample. While thermal stability might be inferred from several properties or tests, it does not represent a direct measurement in the same sense as the other attributes listed.