A sample is statistically valid if it is collected using what method?

A sample is considered statistically valid when it is collected using scientific sampling methods. This approach ensures that the sample accurately represents the population from which it is drawn, allowing for reliable conclusions to be drawn from the data collected.

Scientific sampling methods often involve strategies such as random sampling, stratified sampling, or systematic sampling. These methods minimize bias and provide a framework that enhances the validity and reliability of the results, making it possible to generalize findings from the sample to a larger population.

Casual sampling techniques, expert opinion sampling, and random judgment sampling do not adhere to the rigorous methodologies necessary to ensure scientific validity. They might introduce bias or fail to represent the population adequately, leading to conclusions that may not be reliable or applicable. Thus, the emphasis on scientific methods is critical for ensuring that data collection is grounded in statistically sound practices.