Validity: Validity refers to whether a measurement accurately measures what it intends to measure. In the context of data collection, it means ensuring that the survey questions or methods used effectively capture the desired information.
Sampling Bias: Sampling bias occurs when certain individuals or groups within a population are more likely to be included in a survey sample than others, leading to skewed or unrepresentative results.
Data Reliability: Data reliability relates to how consistent and stable data is over time. It involves conducting studies repeatedly under similar conditions and obtaining similar results each time.