Final answer:
In scientific measurements, validity can refer to the accuracy and sensitivity of an instrument, ensuring it measures what it is intended to capture. Accuracy describes how close the measurement is to the true value, while sensitivity indicates the ability to detect small differences. An instrument must be both reliable and accurate for its measurements to be valid.
Step-by-step explanation:
Validity in scientific measurements implies that a tool or instrument measures exactly what it is supposed to. There are several aspects to consider when talking about validity, but in the context provided, two things that validity can refer to are accuracy and sensitivity. It is important to differentiate these concepts from others like precision and reliability. Accuracy is a measure of how close a measurement is to the correct or accepted value. For example, if you measure a length of paper that is known to be 11.0 inches and get a measurement of 11.1 inches, this is very close to the correct value, and we can say the measurement is quite accurate. However, if the measurement was 12 inches, it would be inaccurate. Sensitivity, on the other hand, refers to the instrument's ability to detect small differences or the smallest increment it can measure. It's not explicitly mentioned in the reference but is related to the validity of an instrument as it must be able to accurately detect these small changes to be valid for the measurements it is intended to capture. Reliability indicates that an instrument can consistently produce the same result. This does not guarantee accuracy, as an instrument could consistently produce the same wrong result. Valid measurements require instruments that are capable of both reliable and accurate readings, ensuring that the data collected correctly represents what is being measured. Precision is about the consistency of repeated measurements. If an instrument gives you very similar readings each time you measure the same quantity, then the instrument is said to be precise. However, precision does not entail accuracy. An instrument can provide consistent but inaccurate measurements, which ultimately would not be considered valid.