A valid method refers to a reliable and trustworthy approach or procedure used to collect data or conduct research that accurately measures what it intends to measure.
Reliability is the consistency and stability of measurements or results over time. It ensures that if the same study is conducted multiple times, similar results will be obtained each time.
Sampling: Sampling involves selecting a subset of individuals (or items) from a larger population for research purposes. It aims to represent the larger population accurately and provide generalizable findings.
Internal validity refers to the extent to which an experiment's design allows for confident conclusions about cause-and-effect relationships between variables within the study.