In scientific research, measurements must be both ___ and ___.

In scientific research, it is essential that measurements are valid and reliable. Validity refers to the degree to which a measurement actually reflects the concept or phenomenon that it is intended to measure. This means that the methods and tools used must accurately capture the true attributes of the subject of study. Reliability, on the other hand, refers to the consistency of a measurement—if the same measurement is repeated under the same conditions, it should yield the same results over time. Together, validity and reliability ensure that research findings are sound and can be trusted, leading to credible conclusions and potential applications in the field.

While the other concepts related to the other choices are important in various contexts, they do not encompass the fundamental requirements for measurements in scientific research as effectively as validity and reliability do. For example, comprehensive and accurate measurements might be useful, but without reliability, even accurate measurements can lead to differing results if repeated. Similarly, while it's important for scientific concepts to be simple and understandable to communicate findings effectively, these traits do not directly contribute to the integrity of the measurements themselves.